Work

Nondegenerate Noise-Resilient Superconducting Qubit

Year: 2025

Type: article

Abstract: We propose a superconducting qubit based on engineering the first and second harmonics of the Josephson energy and phase relation E J 1 cos φ and E J 2 cos 2 φ . By constructing a circuit such that E J 2 is negative and | E J 1 | ≪ | E J 2 | , we create a periodic potential with two nondegenerate minima. The qubit, which we dub “harmonium,” is formed from the lowest-energy states of each minimum. Bit-flip protection of the qubit arises due to the localization of each qubit state to their respective minima, while phase-flip protection can be understood by considering the circuit within the Born-Oppenheimer approximation. We demonstrate with time-domain simulations that single- and two-qubit gates can be performed in approximately 100 ns. Finally, we compute the qubit coherence times using numerical diagonalization of the complete circuit in conjunction with state-of-the-art noise models. We estimate out-of-manifold heating times on the order of milliseconds, which can be treated as erasure errors using conventional dispersive readout. We estimate pure-dephasing times on the order of many tens of milliseconds, and bit-flip times on the order of seconds.

Source: PRX Quantum

DOI: 10.1103/dd96-gcb6

Authors: Max Hays, Junghyun Kim, William D. Oliver

Institution: Massachusetts Institute of Technology

Language: English

Topic: Quantum Information and Cryptography

Subfield: Artificial Intelligence

Field: Computer Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,450