Exhibit 16.1

March 26, 2026

Office of the Chief Accountant

Securities and Exchange Commission

100 F Street, NE

Washington, D.C. 20549

Ladies and Gentlemen:

We have read ColdQuanta, Inc. (legal successor of Churchill Capital Corp X) statements included under Item 4.01 of its Form 8-K dated March 26, 2026. We agree with the statements concerning our Firm under Item 4.01, in which we were informed of our dismissal on March 23, 2026, following completion of the Company’s annual audit as of and for the year ended December 31, 2025, which consists only of the accounts of the pre-Business Combination Special Purpose Acquisition Company. We are not in a position to agree or disagree with other statements contained therein.

Very truly yours,

/s/ WithumSmith+Brown, PC

New York, New York