Dissipative cat qubits for quantum computing*

The massive hardware overhead required to implement quantum error correction remains a big roadblock towards the realization of a fault-tolerant, universal quantum computer.

Bosonic codes are a promising approach to decrease significantly the hardware overhead by implementing a first layer of error correction at the physical qubit level.

In particular, dissipative cat qubits suppress bit-flip errors exponentially over orders of magnitude, such that in principle only phase-flip errors need an active error correction. It is estimated that this approach would allow to run Shor's algorithm with 60 times less physical qubits than needed with the surface code.

In this talk, I will present our work to engineer and increase the peculiar kind of dissipation, known as two-photon dissipation, allowing to suppress exponentially the bit-flips of cat qubits. I will also present our results realizing quantum gates on cat qubits that leverage the two-photon dissipation in order to preserve the exponential suppression of bit-flips during the gate, a key requirement for the repetition code correcting for phase-flip errors.

[1] Gouzien, Ruiz, Le Régent, Guillaud and Sangouard, Phys. Rev. Lett. 131, 040602 (2023) - Computing 256-bit Elliptic Curve Logarithm in 9 Hours with 126133 Cat Qubits

[2] Réglade, Bocquet, Gautier, Marquet, Albertinale, Pankratova, Hallén, Rautschke, Sellem, Rouchon, Sarlette, Mirrahimi, Campagne-Ibarcq, Lescanne, Jezouin and Leghtas, arXiv:2307.06617 (2023) - Quantum control of a cat-qubit with bit-flip times exceeding ten seconds

[3] Marquet, Essig, Cohen, Cottet, Murani, Albertinale, Dupouy, Bienfait, Peronnin, Jezouin, Lescanne and Huard, arXiv:2307.06761 (2023) - Autoparametric resonance extending the bit-flip time of a cat qubit up to 0.3 s