NOTICE IS HEREBY GIVEN that an extraordinary general meeting (the “extraordinary general meeting”) of Supernova Partners Acquisition Company II, Ltd., a Cayman Islands exempted company (“Supernova”), will be held at                , Eastern Time, on                , 2021, at the offices of                  located at                  , and virtually via live webcast at                  , on such other date and at such other place to which the meeting may be adjourned. As all shareholders are no doubt aware, due to the current novel coronavirus global pandemic, there are restrictions in place in many jurisdictions relating to the ability to conduct meetings. As part of our precautions regarding we are planning for the possibility that the meeting may be held virtually over the internet, but the physical location of the meeting will remain at the location specified above for the purposes of our amended and restated memorandum and articles of association. You are cordially invited to attend the extraordinary general meeting, which will be held for the following purposes:

Each of the Business Combination Proposal, the Domestication Proposal, the Proposed Charter and Bylaws Proposal, the NYSE Proposal, the Director Election Proposal, the Equity Incentive Plan Proposal and the Employee Stock Purchase Plan Proposal is conditioned on the approval and adoption of each of the other Condition Precedent Proposals. The Advisory Governing Documents Proposals are advisory proposals that are not conditions precedent to the consummation of the Business Combination and a vote against will have no impact on the provisions of the new certificate of incorporation or new bylaws of New Rigetti. The Adjournment Proposal is not conditioned on any other proposal.

This proxy statement/prospectus and accompanying proxy card is being provided to Supernova’s shareholders in connection with the solicitation of proxies to be voted at the extraordinary general meeting and at any adjournment of the extraordinary general meeting. ”

Holders of units must elect to separate the units into the underlying public shares and warrants prior to exercising redemption rights with respect to the public shares. If holders hold their units in an account at a brokerage firm or bank, holders must notify their broker or bank that they elect to separate the units into the underlying public shares and warrants, or if a holder holds units registered in its own name, the holder must contact AST, Supernova’s transfer agent, directly and instruct them to do so. The redemption rights include the requirement that a holder must identify itself in writing as a beneficial holder and provide its legal name, phone number and address to AST in order to validly redeem its shares. Public shareholders may elect to redeem public shares regardless of if or how they vote in respect of the Business Combination Proposal. If the Business Combination is not consummated, the public shares will be returned to the respective holder, broker or bank. If the Business Combination is consummated, and if a public shareholder properly exercises its right to redeem all or a portion of the public shares that it holds and timely delivers its share certificates (if any) and other redemption forms (as applicable) to AST, Supernova’s transfer agent, New Rigetti will redeem such public shares for a price, payable in cash, equal to the pro rata portion of the trust account established at the consummation of Supernova’s initial public offering (the “trust account”), calculated as of two business days prior to the consummation of the Business Combination. For illustrative purposes, as of June 30, 2021, this would have amounted to approximately $10.00 per issued and outstanding public share. If a public shareholder exercises its redemption rights in full, then it will be electing to exchange its public shares for cash and will no longer own public shares. See “” in this proxy statement/prospectus for a detailed description of the procedures to be followed if you wish to redeem your public shares for cash.

Supernova Partners II LLC, a Cayman Islands exempted company (the “Sponsor”) and each of our directors and officers (the “Initial Shareholders”) have, pursuant to the sponsor support agreement with the Sponsor, Rigetti and Supernova’s directors and officers (the “Sponsor Support Agreement”), agreed to, among other things, vote all of their ordinary shares in favor of the proposals being presented at the extraordinary general meeting and waive their anti-dilution rights with respect to their Class B ordinary shares in connection with the consummation of the Business Combination. Such shares will be excluded from the pro rata calculation used to determine the redemption price. As of the date of this proxy statement/prospectus, the Initial Shareholders own approximately 20% of the issued and outstanding ordinary shares. See “” in the accompanying proxy statement/prospectus for more information related to the Sponsor Support Agreement.

Merger Agreement would waive any such closing condition. In addition, in no event will Supernova redeem public shares in an amount that would cause New Rigetti’s net tangible assets (as determined in accordance with Rule of the Exchange Act) to be less than $5,000,001 after giving effect to the transactions contemplated by the Merger Agreement and the PIPE Financing (as defined in the proxy statement/prospectus). Nor will Supernova redeem public shares in an amount that would cause the aggregate cash proceeds available for release from the trust account in connection with the transactions contemplated in the Merger Agreement (including the PIPE Financing) to be less than $165 million.

The approval of each of the Domestication Proposal and the Proposed Charter and Bylaws Proposal requires a special resolution under Cayman Islands law, being the affirmative vote of the holders of at least (2/3) of the ordinary shares who, being present in person or by proxy and entitled to vote at the extraordinary general meeting, vote at the extraordinary general meeting. The approval of each of the Business Combination Proposal, each of the Advisory Governing Documents Proposals, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal, the NYSE Proposal, the Director Election Proposal and the Adjournment Proposal requires an ordinary resolution under Cayman Islands law, being the affirmative vote of a majority of the ordinary shares represented in person or by proxy and entitled to vote thereon and who vote at the extraordinary general meeting. Because the Domestication Proposal involves a vote to continue Supernova outside the jurisdiction of the Cayman Islands, holders of Class B ordinary shares will have ten votes per Class B ordinary share and holders of Class A ordinary shares will have one vote per Class A ordinary share for purposes of the Domestication Proposal. Holders of Class B ordinary shares and Class A ordinary shares will have one vote per share on all other proposals.

Your attention is directed to the remainder of the proxy statement/prospectus following this notice (including the Annexes and other documents referred to herein) for a more complete description of the proposed Business Combination and related transactions and each of the proposals. You are encouraged to read this proxy statement/prospectus carefully and in its entirety, including the Annexes and other documents referred to herein. If you have any questions or need assistance voting your ordinary shares, please contact Morrow Sodali LLC, our proxy solicitor, by calling (800) or banks and brokers can call collect at (203) or by emailing Supernova.info@investor.morrowsodali.com.

of the Board of Directors

This proxy statement/prospectus includes industry and market data obtained from periodic industry publications, third-party studies and surveys, as well as from filings of public companies in our industry and internal company surveys. These sources include government and industry sources. Industry publications and surveys generally state that the information contained therein has been obtained from sources believed to be reliable. Although we believe the industry and market data to be reliable as of the date of this proxy statement/prospectus, this information could prove to be inaccurate. Industry and market data could be wrong because of the method by which sources obtained their data and because information cannot always be verified with complete certainty due to the limits on the availability and reliability of raw data, the voluntary nature of the data gathering process and other limitations and uncertainties. Each publication, study and report speaks as of its original publication date (and not as of the date of this proxy statement/prospectus). Certain of these publications, studies and reports were published before and therefore do not reflect any impact any specific market or globally. In addition, we do not know all of the assumptions regarding general economic conditions or growth that were used in preparing the forecasts from the sources relied upon or cited herein. The industry in which we operate is subject to a high degree of uncertainty and risk due to a variety of factors, including those described in the section titled “Risk Factors.” These and other factors could cause results to differ materially from those expressed in these publications and reports.

“” are to the amended and restated articles of association of Supernova;

“” are to American Stock Transfer & Trust Company;

“” are to the Domestication, the Merger and other transactions contemplated by the Merger Agreement, collectively, including the PIPE Financing;

“” are to the Companies Act (As Revised) of the Cayman Islands as the same may be amended from time to time;

“” are to the Class A ordinary shares, par value $0.0001 per share, of Supernova, which will automatically convert, on a basis, into shares of New Rigetti Common Stock in connection with the Domestication;

“” are to the 8,625,000 Class B ordinary shares, par value $0.0001 per share, of Supernova outstanding as of the date of this proxy statement/prospectus that were initially issued to our Sponsor in a private placement prior to our initial public offering and of which 34,500 were transferred to each of the Supernova independent directors in February 2021, and, in connection with the Domestication, will automatically convert, on a basis, into shares of New Rigetti Common Stock;

“” are to the closing of the Business Combination;

“” are to the date on which the Closing actually occurs;

“” are to the Business Combination Proposal, the Domestication Proposal, the Proposed Charter and Bylaws Proposal, the NYSE Proposal, the Director Election Proposal, the Equity Incentive Plan Proposal and the Employee Stock Purchase Plan Proposal, collectively;

“” are to the transfer by way of continuation and deregistration of Supernova from the Cayman Islands and the continuation and domestication of Supernova as a corporation incorporated in the State of Delaware;

“e” are to the time at which the Merger becomes effective;

“” are to the New Rigetti 2021 Employee Stock Purchase Plan to be considered for adoption and approval by the shareholders pursuant to the Employee Stock Purchase Plan Proposal;

“” are to the extraordinary general meeting of Supernova at                , on                , 2021, located at                , and virtually via live webcast at                , or at such other time, on such other date and at such other place to which the meeting may be adjourned;

“” are to the Memorandum of Association and the Articles of Association;

“” are to Class B ordinary shares initially issued to the Sponsor in a private placement prior to Supernova’s initial public offering and the Class A ordinary shares that will be issued upon the automatic conversion of the Class B ordinary shares at the time of our initial business combination or earlier at the option of the holders thereof;

“” are to generally accepted accounting principles in the United States, as applied on a consistent basis;

“” are to Supernova’s initial public offering that was consummated on March 4, 2021;

“” are to the New Rigetti 2021 Equity Incentive Plan to be considered for adoption and approval by the shareholders pursuant to the Equity Incentive Plan Proposal;

“” are to Sponsor and each of the directors and officers of Supernova;

“” are to the amended and restated memorandum of association of Supernova;

“” are to the merger of First Merger Sub with and into Rigetti pursuant to the Merger Agreement, with Rigetti as the surviving company in the Merger and the merger of Rigetti with and into Second Merger Sub, with Second Merger Sub being the surviving entity in the merger, and after giving effect to such Merger, Rigetti becoming a wholly owned subsidiary of New Rigetti;

“” are to that certain Merger Agreement, dated October 6, 2021, by and among Supernova, Supernova Merger Sub, Inc., Supernova Romeo Merger Sub, LLC and Rigetti, and as may be amended, supplemented or otherwise modified from time to time;

“” are to Rigetti Computing, Inc., a Delaware corporation, upon and after the Domestication and the consummation of the Business Combination;

“” are to the board of directors of New Rigetti;

“” are to the common stock, par value $0.0001 per share, of New Rigetti;

“” are to the preferred stock, par value $0.0001 per share, of New Rigetti;

“” are to the New York Stock Exchange;

“” are to our Class A ordinary shares and our Class B ordinary shares;

“” are to the transactions contemplated by the Subscription Agreements, pursuant to which the PIPE Investors have collectively committed to subscribe for an aggregate of 10,251,000 shares of New Rigetti Common Stock for an aggregate purchase price of $102,510,000 to be consummated in connection with Closing;

“” are to the 4,450,000 private placement warrants outstanding as of the date of this proxy statement/ prospectus that were issued to our Sponsor as part of the closing of our initial public offering, which are substantially identical to the public warrants sold as part of the units in the initial public offering, subject to certain limited exceptions;

“” are to giving pro forma effect to the Business Combination, including the Merger and the PIPE Financing;

“” are to the proposed bylaws of New Rigetti to be effective upon the Domestication attached to this proxy statement/prospectus as Annex D;

“” or “” are to the proposed certificate of incorporation of New Rigetti to be effective upon the Domestication attached to this proxy statement/prospectus as Annex C;

“” are to the Proposed Certificate of Incorporation and the Proposed Bylaws;

“” are to holders of public shares, whether acquired in Supernova’s initial public offering or acquired in the secondary market;

“” are to the currently outstanding 34,500,000 Class A ordinary shares of Supernova, whether acquired in Supernova’s initial public offering or acquired in the secondary market;

“” are to the currently outstanding 8,625,000 redeemable warrants to purchase Class A ordinary shares of Supernova that were issued by Supernova in its initial public offering;

“” are to each redemption of public shares for cash pursuant to the Existing Governing Documents;

“” are to the registration statement of which this proxy statement/prospectus forms a part;

“” are to Rigetti Holdings, Inc., a Delaware corporation, and its consolidated subsidiaries since the consummation of the Rigetti Holding Company Reorganization on October 5, 2021 and prior to the consummation of the Business Combination, and to Rigetti & Co, Inc. and its consolidated subsidiaries prior to the consummation of the Rigetti Holding Company Reorganization on October 5, 2021;

“” means the shares of common stock, par value $0.000001 per share, of Rigetti, which shares have been designated as Class A Common Stock and the shares of common stock, par value $0.000001 per share, of Rigetti, which shares have been designated as Class B Common Stock;

“” means the holding company reorganization pursuant to which (i) Rigetti & Co, Inc. established Rigetti Holdings, Inc. and Rigetti Intermediate Merger Sub Inc., each as wholly owned subsidiaries of Rigetti & Co, Inc., (ii) on October 5, 2021, pursuant to an Agreement and Plan of Merger (the “Holding Company Merger Agreement”) by and among Rigetti & Co, Inc., Rigetti Holdings, Inc. and Rigetti Intermediate Merger Sub, Inc., dated as of October 5, 2021, Rigetti Intermediate Merger Sub, Inc. merged with and into Rigetti & Co, Inc., with Rigetti & Co, Inc. surviving such merger as a wholly owned subsidiary of Rigetti Holdings, Inc., with all of the outstanding equity securities of Rigetti & Co, Inc. exchanged for identical equity securities of Rigetti Holdings, Inc. and (iii) on October 6, Rigetti & Co, Inc. was converted into a Delaware limited liability company and continues as “Rigetti & Co, LLC”;

“” means, collectively, the shares of preferred stock, par value $0.000001 per share, of Rigetti, of which shares have been designated as Series C Preferred Stock and Series Preferred Stock;

“” means an award of restricted stock units based on shares of Rigetti Common Stock (whether to be settled in cash or shares), granted under the 2013 Plan;

“” are the current and former holders of Rigetti shares prior to the consummation of the Business Combination;

“” means the approval of the Merger Agreement and the Transactions, including the Mergers and the making of any filings, notices or information statements in connection with the foregoing, in accordance with the terms and subject to the conditions of Rigetti’s governing documents and applicable law;

“” are to the Securities and Exchange Commission;

“” are to the Securities Act of 1933, as amended;

“” are to Supernova Partners II LLC, a Cayman Islands exempted company;

“” are to are to that certain Sponsor Agreement, dated as of October 6, 2021, by and among the Sponsor, Supernova and Rigetti, as amended and modified from time to time;

“” are to the subscription agreements, entered into by Supernova and each of the PIPE Investors in connection with the PIPE Financing;

“,” “,” “” or “” are to Supernova Partners Acquisition Company II, Ltd., a Cayman Islands exempted company, prior to the consummation of the Business Combination;

“” are to Supernova’s board of directors;

“” are Supernova’s officers, directors and Sponsor investors.

“” are to AST, Supernova’s transfer agent;

“” are to the trust account established at the consummation of Supernova’s initial public offering that holds the proceeds of the initial public offering and is maintained by AST, acting as trustee;

“” are to the units of Supernova, each unit representing one Class A ordinary share and of one warrant to acquire one Class A ordinary share, that were offered and sold by Supernova in its initial public offering and in its concurrent private placement; and

“” are to the public warrants and the private placement warrants.

The forward-looking statements contained in this proxy statement/prospectus are based on current expectations and beliefs concerning future developments and their potential effects on us and/or Rigetti. There can be no assurance that future developments affecting us and/or Rigetti will be those that we and/or the Rigetti have anticipated. These forward-looking statements involve a number of risks, uncertainties (some of which are beyond our control or the control of Rigetti) or other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements. These risks and uncertainties include, but are not limited to, those factors described under the heading “” Should one or more of these risks or uncertainties materialize, or should any of our assumptions prove incorrect, actual results may vary in material respects from those projected in these forward-looking statements. Some of these risks and uncertainties may in the future be amplified by the outbreak and there may be additional risks that we consider immaterial or which are unknown. It is not possible to predict or identify all such risks. Neither we nor Rigetti undertake any obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

Before any shareholder grants its proxy or instructs how its vote should be cast or vote on the proposals to be put to the extraordinary general meeting, such stockholder should be aware that the occurrence of the events described in the “” section and elsewhere in this proxy statement/prospectus may adversely affect us.

    Supernova shareholders are being asked to consider and vote upon, among other proposals, a proposal to approve and adopt the Merger Agreement and approve the transactions contemplated thereby, including the Business Combination. In accordance with the terms and subject to the conditions of the Merger Agreement, among other things, in connection with the Domestication, immediately prior to (but no later than the day preceding) the Closing Date, (i) Supernova will be renamed “Rigetti Computing, Inc.,” and (ii) each share of Rigetti outstanding as of immediately prior to the Effective Time will be exchanged for shares of New Rigetti Common Stock based on an implied equity value of $1,041,000,000 and each Rigetti option or warrant will convert into options or warrants to purchase New Rigetti Common Stock. See “.”

The approval of each of the Business Combination Proposal, each of the Advisory Governing Documents Proposals, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal, the NYSE Proposal, the Director Election Proposal and the Adjournment Proposal requires an ordinary resolution under Cayman Islands law, being the affirmative vote of a majority of the ordinary shares represented in person or by proxy and entitled to vote thereon and who vote at the extraordinary general meeting, and each of the Domestication Proposal, and the proposal to approve by special resolution the adoption and approval of the proposed new certificate of incorporation and proposed new bylaws of New Rigetti (the “Proposed Charter and Bylaws Proposal”) requires a special resolution under Cayman Islands law, being the affirmative vote of the holders of at least (2/3) of the ordinary shares who, being present in person or by proxy and entitled to vote at the extraordinary general meeting and, vote at the extraordinary general meeting. Because the Domestication Proposal involves a vote to continue Supernova outside the jurisdiction of the Cayman Islands, holders of Class B ordinary shares will have ten votes per Class B ordinary share and holders of Class A ordinary shares will have one vote per Class A ordinary share for purposes of the Domestication Proposal. Holders of Class B ordinary shares and Class A ordinary shares shall have one vote per share on all other proposals.

In connection with the Domestication, immediately prior to (but no later than the day preceding) the Closing Date: (i) each issued and outstanding Class A ordinary share and each issued and outstanding Class B ordinary share, of Supernova will be converted into one share of common stock, par value $0.0001 per share, of New Rigetti; (ii) each issued and outstanding whole warrant to purchase Class A ordinary shares of Supernova will automatically represent the right to purchase one share of New Rigetti Common Stock at an exercise price of $11.50 per share on the terms and conditions set forth in the Supernova warrant agreement; (iii) the governing documents of Supernova will be amended and restated and become the certificate of incorporation and the bylaws of New Rigetti as described in this proxy statement/prospectus; and (iv) Supernova’s name will change to “Rigetti Computing, Inc.” In connection with clauses (i) and (ii) of this paragraph, each issued and outstanding unit of Supernova that has not been previously separated into the underlying Class A ordinary shares of Supernova and the underlying warrants of Supernova prior to the Domestication will be cancelled and will entitle the holder thereof to one share of New Rigetti Common Stock and of one warrant representing the

right to purchase one share of New Rigetti Common Stock at an exercise price of $11.50 per share on the terms and subject to the conditions set forth in the Supernova warrant agreement. See “.”

The provisions of the Proposed Governing Documents will differ in certain material respects from the Existing Governing Documents. Please see “” below.

    At the extraordinary general meeting, Supernova is asking holders of its ordinary shares to consider and vote upon twelve (12) separate proposals:

The existence of financial and personal interests of one or more of Supernova’s directors results in conflicts of interest on the part of such director(s) between what he, she or they may believe is in the best interests of Supernova and its shareholders and what he, she or they may believe is best for himself, herself or themselves in determining to recommend that shareholders vote for the proposals. In addition, Supernova’s officers have interests in the Business Combination that may conflict with your interests as a shareholder. See the section entitled “” for a further discussion of these considerations.

    Supernova is a blank check company incorporated on December 22, 2020 as a Cayman Islands exempted company for the purpose of effecting a merger, share exchange, asset acquisition, share purchase, reorganization or similar business combination with one or more businesses. Although Supernova may pursue an acquisition opportunity in any business, industry, sector or geographical location, for purposes of consummating the initial business combination, Supernova has focused on the technology industry. Supernova is not permitted under its Existing Governing Documents to effect a business combination with a blank check company or a similar type of company with nominal operations.

financial and other information provided by Rigetti in the course of negotiations, the Supernova Board believes that the Business Combination with Rigetti presents an attractive business combination opportunity and is in the best interests of Supernova and its shareholders. The board of directors did consider certain potentially material negative factors in arriving at that conclusion. These factors are discussed in greater detail in the sections entitled “” and “.”

    No. The Supernova Board did not obtain a third-party valuation or fairness opinion in connection with its determination to approve the Business Combination. However, Supernova’s management, the members of the Supernova Board and the other representatives of Supernova have substantial experience in evaluating the operating and financial merits of companies similar to Rigetti and reviewed certain financial information of Rigetti and compared it to certain publicly traded companies, selected based on the experience and the professional judgment of Supernova’s management team, which enabled them to make the necessary analyses and determinations regarding the Business Combination. Accordingly, investors will be relying solely on the judgment of the Supernova Board in valuing Rigetti’s business and assuming the risk that the Supernova Board may not have properly valued such business.

    On the Closing Date, First Merger Sub will merge with and into Rigetti, with Rigetti being the surviving entity in the merger, and immediately following the First Merger, Rigetti will merge with and into Second Merger Sub, with Second Merger Sub being the surviving entity in the merger. In connection with the Closing, Supernova will change its name to “Rigetti Computing, Inc.” In accordance with the terms and subject to the conditions of the Merger Agreement, at the Effective Time, each share of Rigetti outstanding as of immediately prior to the Effective Time will be exchanged for shares of New Rigetti Common Stock and each Rigetti option or warrant will convert into options or warrants to purchase New Rigetti Common Stock.

    The implied Rigetti equity value of $1,041,000,000 plus the aggregate exercise price of in the money Rigetti Warrants and Rigetti Options, in each case, outstanding prior to the effective time of the First Merger, was determined based on an implied pro forma enterprise value of New Rigetti of approximately $1,152,000,000,

    Following the Closing, it is expected that the New Rigetti Board will consist of                                                                  . Please see the section entitled “” for further information.

    As of the date of this proxy statement/prospectus, there are (i) 34,500,000 Class A ordinary shares outstanding underlying units issued in Supernova’s initial public offering, and (ii) 8,625,000 Class B ordinary shares outstanding held by Supernova’s Initial Shareholders. As of the date of this proxy statement/prospectus, there are outstanding 4,450,000 private placement warrants held by the Sponsor and 8,625,000 public warrants. Each whole warrant entitles the holder thereof to purchase one Class A ordinary share and, following the Domestication, will entitle the holder thereof to purchase one share of New Rigetti Common Stock. Therefore, as of the date of this proxy statement/prospectus (without giving effect to the Business Combination or the PIPE Financing or the conversion of the working capital loan into warrants and assuming that none of Supernova’s outstanding public shares are redeemed in connection with the Business Combination), Supernova’s fully diluted share capital, giving effect to the exercise of all of the private placement warrants and public warrants, would be 56,200,000 ordinary shares.

The approval of the Domestication Proposal is a condition to closing the Business Combination under the Merger Agreement. The approval of the Domestication Proposal requires a special resolution under Cayman Islands law, being the affirmative vote of the holders of at least (2/3) of the ordinary shares who, being present in person or by proxy and entitled to vote at the extraordinary general meeting, vote at the extraordinary general meeting. Because the Domestication Proposal involves a vote to continue Supernova outside the jurisdiction of the Cayman Islands, holders of Class B ordinary shares will have ten votes per Class B ordinary share and holders of Class A ordinary shares will have one vote per Class A ordinary share for purposes of the Domestication Proposal. Holders of Class B ordinary shares and Class A ordinary shares shall have one vote per share on all other proposals. Abstentions and broker while considered present for the purposes of establishing a quorum, will not count as votes cast at the extraordinary general meeting, and otherwise will have no effect on a particular proposal.

    The consummation of the Business Combination is conditional, among other things, on the Domestication. Accordingly, in addition to voting on the Business Combination, Supernova’s shareholders also are being asked to consider and vote upon a proposal to approve the Domestication, and replace Supernova’s Existing Governing Documents, in each case, under Cayman Islands law with the Proposed Governing Documents, in each case, under the DGCL, which differ from the Existing Governing Documents in the following material respects:

    In connection with the Domestication, immediately prior to (but no later than the day preceding) the Closing Date: (i) each issued and outstanding Class A ordinary share and each issued and outstanding Class B ordinary share, of Supernova will be converted into one share of common stock, par value $0.0001 per share, of New Rigetti; (ii) each issued and outstanding whole warrant to purchase Class A ordinary shares of Supernova will automatically represent the right to purchase one share of New Rigetti Common Stock at an exercise price of $11.50 per share on the terms and conditions set forth in the Supernova warrant agreement; (iii) each issued and outstanding unit will be converted into a New Rigetti unit; (iv) each issued and outstanding Supernova preference share will continue to exist as a share of preferred stock of New Rigetti; (v) the governing documents of Supernova will be amended and restated and become the certificate of incorporation and the bylaws of New Rigetti as described in this proxy statement/prospectus; and (vi) Supernova’s name will change to “Rigetti Computing, Inc.” In connection with clauses (i) and (ii) of this paragraph, each issued and outstanding unit of Supernova that has not been previously separated into the underlying Class A ordinary shares of Supernova and the underlying warrants of Supernova prior to the Domestication will be cancelled and will entitle the holder thereof to one share of New Rigetti Common Stock and of one warrant representing the right to purchase one share of New Rigetti Common Stock at an exercise price of $11.50 per share on the terms and subject to the conditions set forth in the Supernova warrant agreement. See “.”

    As discussed more fully under “,” it is intended that the Domestication qualify as a “reorganization” within the meaning of Section 368(a)(l)(F) of the U.S. Internal Revenue Code of 1986, as amended (the “Code”). Assuming that the Domestication so qualifies, and subject to the “passive foreign investment company” (“PFIC”) rules discussed below and under “,” U.S. Holders (as defined in “”) will be subject to Section 367(b) of the Code and, as a result:

As discussed more fully under “,” Supernova believes that it is likely classified as a PFIC for U.S. federal income tax purposes. In such case, notwithstanding the U.S. federal income tax consequences of the Domestication discussed in the foregoing, proposed Treasury Regulations under Section 1291(f) of the Code (which have a retroactive effective date), if finalized in their current form, generally would require a U.S. Holder to recognize gain on the exchange of Class A ordinary shares or warrants for New Rigetti Common Stock or warrants pursuant to the Domestication. Any such gain would be taxable income with no corresponding receipt of cash in the Domestication. The tax on any such gain would be imposed at the rate applicable to ordinary income and an interest charge would apply based on a complex set of rules. In addition, the proposed Treasury Regulations provide coordinating rules with other sections of the Code, including Section 367(b), which affect the manner in which the rules under such other sections apply to transfers of PFIC stock. However, it is difficult to predict whether, in what form, and with what effective date, final Treasury Regulations under Section 1291(f) of the Code may be adopted and how any such Treasury Regulations would apply. Importantly, however, U.S. Holders that make or have made certain elections discussed further under “” with respect to their Class A ordinary shares are generally not subject to the same gain recognition rules under the currently proposed Treasury Regulations under Section 1291(f) of the Code. Currently, there are no elections available that apply to warrants, and the application of the PFIC rules to the warrants is unclear. For a more complete discussion of the potential application of the PFIC rules to U.S. Holders as a result of the Domestication, see “.”

Additionally, the Domestication may cause Holders (as defined in “”) to become subject to U.S. federal income withholding taxes on any amounts treated as dividends paid in respect of such Holder’s New Rigetti Common Stock after the Domestication.

The tax consequences of the Domestication are complex and will depend on a holder’s particular circumstances. All holders are urged to consult their tax advisor regarding the tax consequences to them of the Domestication, including the applicability and effect of U.S. federal, state, local and tax laws. For a more complete discussion of the U.S. federal income tax considerations of the Domestication, see “.”

    If you are a holder of public shares, you have the right to request that we redeem all or a portion of your public shares for cash provided that you follow the procedures and deadlines described elsewhere in this proxy statement/prospectus. Public shareholders may elect to redeem all or a portion of the public shares held by them regardless of if or how they vote in respect of the Business Combination Proposal. If you wish to exercise your redemption rights, please see the answer to the next question: “”

The Initial Shareholders have agreed to waive their redemption rights with respect to all of their ordinary shares in connection with the consummation of the Business Combination. Such shares will be excluded from the pro rata calculation used to determine the redemption price.

    In connection with the proposed Business Combination, pursuant to the Existing Governing Documents, Supernova’s public shareholders may request that Supernova redeem all or a portion of such public shares for cash if the Business Combination is consummated. If you are a public shareholder and wish to exercise your right to redeem the public shares, you must:

The address of AST, Supernova’s transfer agent, is listed under the question “” below.

Any corrected or changed written exercise of redemption rights must be received by AST, our transfer agent, prior to the vote taken on the Business Combination Proposal at the extraordinary general meeting.

    No. Holders of issued and outstanding units must elect to separate the units into the underlying public shares and public warrants prior to exercising redemption rights with respect to the public shares. If you hold your units in an account at a brokerage firm or bank, you must notify your broker or bank that you elect to separate the units into the underlying public shares and public warrants, or if you hold units registered in your own name, you must contact AST, our transfer agent, directly and instruct them to do so. The redemption rights include the requirement that a holder must identify itself in writing as a beneficial holder and provide its legal name, phone number and address to AST in order to validly redeem its shares. You are requested to cause your public shares to be separated and your share certificates (if any) and other redemption forms (as applicable) delivered to AST, our transfer agent, by 5:00 p.m., Eastern Time, on                , 2021 (two business days before the extraordinary general meeting) in order to exercise your redemption rights with respect to your public shares.

    The U.S. federal income tax consequences of exercising your redemption rights with respect to your Class A ordinary shares to receive cash from the trust account in exchange for New Rigetti Common Stock depend on your particular facts and circumstances. It is possible that you may be treated as selling such New Rigetti Common Stock and, as a result, recognize capital gain or capital loss. It is also possible that the redemption may be treated as a distribution for U.S. federal income tax purposes depending on the amount of New Rigetti Common Stock that you own or are deemed to own (including through the ownership of New Rigetti warrants). For a more complete discussion of the U.S. federal income tax considerations of an exercise of redemption rights, see “.”

Additionally, because the Domestication will occur prior to the redemption of any shareholder, U.S. Holders (as defined in “”) exercising redemption rights will be subject to the potential tax consequences of Section 367 of the Code as well as potential tax consequences of the U.S. federal income tax rules relating to PFICs. The tax consequences of Section 367 of the Code and the PFIC rules are discussed more fully below under “.”

All holders considering exercising redemption rights are urged to consult their tax advisor on the tax consequences to them of an exercise of redemption rights, including the applicability and effect of U.S. federal, state, local and tax laws.

    Following the closing of our initial public offering, an amount equal to $345,000,000 ($10.00 per unit) of the net proceeds from our initial public offering and the sale of the private placement warrants. As of June 30, 2021, funds in the trust account totaled approximately $345 million and were invested in U.S. government treasury bills with a maturity of 185 days or less or in money market funds investing solely in U.S. Treasuries and meeting certain conditions under the Investment Company Act of 1940, as amended. These funds will remain in the trust account, except for the withdrawal of interest to pay taxes, if any, until the earliest of (i) the completion of Supernova’s initial business combination, (ii) the redemption of any public shares properly tendered in connection with a shareholder vote to amend the Existing Governing Documents to modify the substance and timing of our obligation to redeem 100% of the public shares if Supernova does not complete a business combination by March 4, 2023, or (iii) the redemption of all of the public shares if Supernova is unable to complete a business combination by March 4, 2023 (unless such date is extended in accordance with the Existing Governing Documents), subject to applicable law.

Upon consummation of the Business Combination, the funds deposited in the trust account will be released to pay holders of public shares who properly exercise their redemption rights; to pay transaction fees and expenses associated with the Business Combination; and for working capital and general corporate purposes of New Rigetti following the Business Combination. See “.”

    Our public shareholders are not required to vote “FOR” the Business Combination in order to exercise their redemption rights. Accordingly, the Business Combination may be consummated even though the funds available from the trust account and the number of public shareholders are reduced as a result of redemptions by public shareholders. However, a condition to the consummation of the Business Combination is that the aggregate cash proceeds available for release from the trust account in connection with the transactions contemplated in the Merger Agreement is equal to or greater than $165 million, after deducting Supernova’s unpaid expenses.

In no event will Supernova redeem public shares in an amount that would cause our net tangible assets (as determined in accordance with Rule of the Exchange Act) to be less than $5,000,001 after giving effect to the transactions contemplated by the Merger Agreement and the PIPE Financing.

    The consummation of the Business Combination is conditioned upon, among other things, (i) approval by Supernova’s and Rigetti’s respective stockholders, (ii) the expiration or termination of the waiting period under the HSR Act and the obtaining of any consents required under antitrust laws or foreign direct investment laws in the jurisdictions specified on a schedule, (iii) no law or order enjoining or prohibiting the consummation of the Transactions being in force, (iv) Supernova having at least $5,000,001 of net tangible assets as of the Closing, (v) receipt of approval for listing on the New York Stock Exchange of the shares of Supernova common stock to be issued in connection with the Transactions, (vi) completion of the Domestication, (vii) the effectiveness of this registration statement the accuracy of the parties’ respective representations and warranties (subject to specified materiality thresholds) and the material performance of the parties’ respective covenants and other obligations, (ix) no material adverse effect on Rigetti having occurred since signing that is continuing at

    It is currently expected that the Business Combination will be consummated in the first quarter of 2022. This date depends, among other things, on the approval of the proposals to be put to Supernova shareholders at the extraordinary general meeting. However, such extraordinary general meeting could be adjourned if the Adjournment Proposal is adopted by our shareholders at the extraordinary general meeting and we elect to adjourn the extraordinary general meeting to a later date or dates, if necessary (i) to solicit additional proxies for the purpose of obtaining approval by the shareholders of Supernova for each of the proposals necessary to consummate the transactions contemplated by the Merger Agreement, (ii) for the absence of a quorum or (iii) if the holders of the Class A ordinary shares have elected to redeem a number of Class A ordinary shares as of such time that would reasonably be expected to result in the conditions required for the Closing of the Merger Agreement not to be satisfied; provided that, without the consent of Rigetti, in no event shall the extraordinary general meeting of shareholders be adjourned to a date that is more than fifteen (15) business days later than the most recently adjourned meeting or to a date that is beyond the termination date of the Merger Agreement. For a description of the conditions for the completion of the Business Combination, see “Business Combination Proposal—Conditions to Closing of the Business Combination.”

    Supernova will not complete the Domestication to Delaware unless all other conditions to the consummation of the Business Combination have been satisfied or waived by the parties in accordance with the terms of the Merger Agreement. If Supernova is not able to consummate the Business Combination with Rigetti nor able to complete another business combination by March 4, 2023, we will (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but not more than ten business days thereafter, redeem the public shares, at a price, payable in cash, equal to the aggregate amount then on deposit in the trust account, including interest (which interest shall be net of taxes payable, and less up to $100,000 of interest to pay dissolution expenses), divided by the number of then outstanding public shares, which redemption will completely extinguish public shareholders’ rights as shareholders (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of our remaining shareholders and our board of directors, liquidate and dissolve, subject in each case to our obligations under Cayman Islands law to provide for claims of creditors and the requirements of other applicable laws.

    Neither our shareholders nor our warrant holders have appraisal rights in connection with the Business Combination or the Domestication under Cayman Islands law or under the DGCL.

    You should read this proxy statement/prospectus, including the Annexes and the documents referred to herein, carefully and in their entirety and to consider how the Business Combination will affect you as a shareholder and/or warrant holder. Our shareholders should then vote as soon as possible in accordance with the instructions provided in this proxy statement/prospectus and on the enclosed proxy card.

    If you are a holder of record of ordinary shares on the record date for the extraordinary general meeting, you may vote in person virtually at the extraordinary general meeting, or by submitting a proxy for the extraordinary general meeting. You may submit your proxy by completing, signing, dating and returning the enclosed proxy cards, as applicable, in the envelope.

    No. If your shares are held in a stock brokerage account or by a bank or other nominee, you are considered the “beneficial holder” of the shares held for you in what is known as “street name.” If this is the case, this proxy statement/prospectus may have been forwarded to you by your brokerage firm, bank or other nominee, or its agent. As the beneficial holder, you have the right to direct your broker, bank or other nominee as to how to vote your shares. If you do not provide voting instructions to your broker on a particular proposal on which your broker does not have discretionary authority to vote, your shares will not be voted on that proposal. This is called a “broker Abstentions and broker while considered present for the purposes of establishing a quorum, will not count as votes cast at the extraordinary general meeting, and otherwise will have no effect on a particular proposal. If you decide to vote, you should provide instructions to your broker, bank or other nominee on how to vote in accordance with the information and procedures provided to you by your broker, bank or other nominee.

    The extraordinary general meeting will be held at                , Eastern Time, on                , 2021, at the offices of                  located at                  , and virtually live via webcast at                  , or such other date, time and place to which such meeting may be adjourned or postponed, to consider and vote upon the proposals.

    We intend to hold the extraordinary general meeting in person. However, we are sensitive to the public health and travel concerns our shareholders may have and recommendations that public health officials may issue in light of the evolving coronavirus situation. As a result, we may impose additional procedures or limitations on meeting attendees. We plan to announce any such updates in a press release filed with the SEC and on our proxy website at                , and we encourage you to check this website prior to the meeting if you plan to attend.

Q:    

A:    As a registered shareholder, you will receive the proxy card from AST. The form contains instructions on how to attend the virtual meeting including the URL address, along with your control number. You will need your control number for access. If you do not have your control number, contact AST at the phone number or address below. AST support contact information is as follows: (718) or email help@astfinancial.com.

You can to attend the virtual meeting starting at                , Eastern Time, on                , 2021. Enter the URL address into your browser                , enter your control number, name and email address. Once you

you can vote or enter questions in the chat box. At the start of the meeting you will need to in using your control number and will also be prompted to enter your control number if you vote during the meeting.

If you do not have internet capabilities, you can listen only to the meeting by dialing (800) (toll-free) within the United States and Canada or (718) (standard rates apply) outside of the United States and Canada and, when prompted, entering the pin number. This you will not be able to vote or enter questions during the meeting.

    Given the ongoing and dynamic nature of the circumstances, it is difficult to predict the impact of the coronavirus outbreak on the business of Supernova and Rigetti, and there is no guarantee that efforts by Supernova and Rigetti to address the adverse impacts of the coronavirus will be effective. The extent of such impact will depend on future developments, which are highly uncertain and cannot be predicted, including new information which may emerge concerning the severity of the coronavirus and actions taken to contain the coronavirus or its impact, among others. If Supernova or Rigetti are unable to recover from a business disruption on a timely basis, the Business Combination and New Rigetti’s business, financial condition and results of operations following the completion of the Business Combination would be adversely affected. The Business Combination may also be delayed and adversely affected by the coronavirus outbreak and become more costly. Each of Supernova and Rigetti may also incur additional costs to remedy damages caused by any such disruptions, which could adversely affect its financial condition and results of operations.

    We have fixed                , 2021 as the record date for the extraordinary general meeting. If you were a shareholder of Supernova at the close of business on the record date, you are entitled to vote on matters that come before the extraordinary general meeting. However, a shareholder may only vote his or her shares if he, she or they is present in person or is represented by proxy at the extraordinary general meeting.

    With the exception of our Initial Shareholders, who are entitled to ten votes for each Class B ordinary share they hold for purposes of voting on the Domestication Proposal, Supernova shareholders are entitled to one vote at the extraordinary general meeting for each ordinary share held of record as of the record date. As of the close of business on the record date for the extraordinary general meeting, there were 34,500,000 Class A ordinary shares issued and outstanding and 8,625,000 Class B ordinary shares issued and outstanding, all of which are held by the Initial Shareholders.

    A quorum of Supernova shareholders is necessary to hold a valid meeting. A quorum will be present at the extraordinary general meeting if one or more shareholders who together hold not less than a majority of the issued and outstanding ordinary shares entitled to vote at the extraordinary general meeting are represented in person or by proxy at the extraordinary general meeting. As of the record date for the extraordinary general meeting, 21,562,501 ordinary shares would be required to achieve a quorum for each proposal contained in this proxy statement.

    The following votes are required for each proposal at the extraordinary general meeting:

    The Supernova Board believes that the Business Combination Proposal and the other proposals to be presented at the extraordinary general meeting are in the best interest of Supernova and its shareholders and unanimously recommends that its shareholders vote “FOR” the Business Combination Proposal, “FOR” the Domestication Proposal, “FOR” the Proposed Charter and Bylaws Proposal, “FOR” each of the separate Advisory Governing Documents Proposals, “FOR” the NYSE Proposal, “FOR” the Director Election Proposal, “FOR” the Equity Incentive Plan Proposal, “FOR” the Employee Stock Purchase Plan Proposal, and “FOR” the Adjournment Proposal, in each case, if presented to the extraordinary general meeting.

The existence of financial and personal interests of one or more of Supernova’s directors results in conflicts of interest on the part of such director(s) between what he, she or they may believe is in the best interests of Supernova and its shareholders and what he, she or they may believe is best for himself, herself or themselves in determining to recommend that shareholders vote for the proposals. In addition, Supernova’s officers have interests in the Business Combination that may conflict with your interests as a shareholder. See the section entitled “” for a further discussion of these considerations.

    Unlike some other blank check companies in which the Initial Shareholders agree to vote their shares in accordance with the majority of the votes cast by the public shareholders in connection with an initial business combination, our Initial Shareholders have agreed to vote all of their shares in favor of all the proposals being presented at the extraordinary general meeting. As of the date of this proxy statement/prospectus, our Initial Shareholders own approximately 20% of the issued and outstanding ordinary shares.

At any time at or prior to the Business Combination, during a period when they are not then aware of any material nonpublic information regarding us or our securities, our Initial Shareholders, Rigetti and/or their directors, officers, advisors or respective affiliates may purchase public shares from institutional and other investors who vote, or indicate an intention to vote, against any of the Condition Precedent Proposals, or execute agreements to purchase such shares from such investors in the future, or they may enter into transactions with such investors and others to provide them with incentives to acquire public shares or vote their public shares in favor of the Condition Precedent Proposals. Such a purchase may include a contractual acknowledgement that such shareholder, although still the record or beneficial holder of our shares, is no longer the beneficial owner thereof and therefore agrees not to exercise its redemption rights. In the event that our Initial Shareholders, Rigetti and/or their directors, officers, advisors or respective affiliates purchase shares in privately negotiated transactions from public shareholders who have already elected to exercise their redemption rights, such selling shareholder would be required to revoke their prior elections to redeem their shares. Our Initial Shareholders, Rigetti, and/or their directors, officers, advisors or respective affiliates may also purchase public shares from institutional and other investors who indicate an intention to redeem our shares, or, if the price per share of our shares falls below $10.00 per share, such parties may seek to enforce their redemption rights. The above-described activity could be especially prevalent in and around the time of Closing. The purpose of such share purchases and other transactions would be to increase the likelihood of satisfaction of the requirements that (i) the Business Combination Proposal, each of the Advisory Governing Documents Proposals, the NYSE Proposal, the Director Election Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal are approved by the affirmative vote of at least a majority of the votes cast by the holders of the issued ordinary shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter, (ii) the Domestication Proposal and the Proposed Charter and Bylaws Proposal are approved by the affirmative vote of at least a (2/3) majority of the votes cast by the holders of the issued ordinary shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter, (iii) otherwise limit the number of public shares electing to redeem and (iv) New Rigetti’s net tangible assets (as determined in accordance with Rule of the Exchange Act) being at least $5,000,001 after giving effect to the transactions contemplated by the Merger Agreement and the PIPE Financing. Our Initial Shareholders, Rigetti and/or their directors, officers, advisors or respective affiliates may also purchase shares from institutional and other investors for investment purposes.

If such transactions are effected, the consequence could be to cause the Business Combination to be consummated in circumstances where such consummation could not otherwise occur. Purchases of shares by the persons described above would allow them to exert more influence over the approval of the proposals to be presented at the extraordinary general meeting and would likely increase the chances that such proposals would be approved. We will file or submit a Current Report on Form to disclose any material arrangements entered into or significant purchases made by any of the aforementioned persons that would affect the vote on the proposals to be put to the extraordinary general meeting or the redemption threshold. Any such report will include descriptions of any arrangements entered into or significant purchases by any of the aforementioned persons.

    The record date for the extraordinary general meeting is earlier than the date of the extraordinary general meeting and earlier than the date that the Business Combination is expected to be completed. If you transfer your public shares after the applicable record date, but before the extraordinary general meeting, unless you grant a proxy to the transferee, you will retain your right to vote at such general meeting.

    Yes. Shareholders may send a later-dated, signed proxy card to our secretary at our address set forth below so that it is received by our secretary prior to the vote at the extraordinary general meeting (which is scheduled to take place on                , 2021) or attend the extraordinary general meeting in person and vote. Shareholders also may revoke their proxy by sending a notice of revocation to our secretary, which must be received by our secretary prior to the vote at the extraordinary general meeting. However, if your shares are held in “street name” by your broker, bank or another nominee, you must contact your broker, bank or other nominee to change your vote.

    If you fail to vote with respect to the extraordinary general meeting and the Business Combination is approved by shareholders and the Business Combination is consummated, you will become a stockholder and/or warrant holder of New Rigetti. If you fail to vote with respect to the extraordinary general meeting and the Business Combination is not approved, you will remain a shareholder and/or warrant holder of Supernova. However, if you fail to vote with respect to the extraordinary general meeting, you will nonetheless be able to elect to redeem your public shares in connection with the Business Combination.

    Our shareholders who exercise their redemption rights must deliver (either physically or electronically) their share certificates to AST, Supernova’s transfer agent, prior to the extraordinary general meeting.

    Shareholders may receive more than one set of voting materials, including multiple copies of this proxy statement/prospectus and multiple proxy cards or voting instruction cards. For example, if you hold your shares in more than one brokerage account, you will receive a separate voting instruction card for each brokerage account in which you hold shares. If you are a holder of record and your shares are registered in more than one name, you will receive more than one proxy card. Please complete, sign, date and return each proxy card and voting instruction card that you receive in order to cast a vote with respect to all of your ordinary shares.

    Supernova will pay the cost of soliciting proxies for the extraordinary general meeting. Supernova has engaged Morrow Sodali LLC to assist in the solicitation of proxies for the extraordinary general meeting. Supernova has agreed to pay Morrow Sodali LLC a fee of $37,500, plus disbursements, and will reimburse

Morrow Sodali LLC for its reasonable expenses and indemnify Morrow Sodali LLC and its affiliates against certain claims, liabilities, losses, damages and expenses. Supernova will also reimburse banks, brokers and other custodians, nominees and fiduciaries representing beneficial owners of Class A ordinary shares for their expenses in forwarding soliciting materials to beneficial owners of Class A ordinary shares and in obtaining voting instructions from those owners. Supernova’s directors and officers may also solicit proxies by telephone, by facsimile, by mail, on the Internet or in person. They will not be paid any additional amounts for soliciting proxies.

    The preliminary voting results will be announced at the extraordinary general meeting. Supernova will publish final voting results of the extraordinary general meeting in a Current Report on Form within four business days after the extraordinary general meeting.

    If you have questions about the Business Combination or if you need additional copies of the proxy statement/prospectus or the enclosed proxy card you should contact:

(800)

You also may obtain additional information about Supernova from documents filed with the SEC by following the instructions in the section entitled If you are a holder of public shares and you intend to seek redemption of your public shares, you will need to deliver your share certificates (if any) and other redemption forms (as applicable) (either physically or electronically) to AST, Supernova’s transfer agent, at the address below prior to the extraordinary general meeting.                  If you have questions regarding the certification of your position or delivery of your share certificates (if any) and other redemption forms (as applicable), please contact:

Phone: (718)