Designing good bosonic quantum codes via creating destructive interference

Understand

Continuous-variable systems protected by bosonic quantum error-correcting codes have emerged as a promising platform for quantum information processing.

• To date, design of codewords has centered on optimizing the occupation of basis states in the error-relevant basis.
• Here, we propose utilizing the phase degree of freedom in basis state probability amplitudes to devise codes that feature destructive interference, and thus reduced overlap, between error codewords.
• To showcase, we first consider the correction of excitation loss using single-mode codes with Fock-space parity structure and show that, with a tailored "two-level" recovery, altering the signs of probability amplitudes can significantly suppress decoherence.