Enhancing dissipative cat qubit protection by squeezing

• URL: http://arxiv.org/abs/2502.07892v1
• Date: Tue, 11 Feb 2025 19:01:05 GMT
• Title: Enhancing dissipative cat qubit protection by squeezing
• Authors: Rémi Rousseau, Diego Ruiz, Emanuele Albertinale, Pol d'Avezac, Danielius Banys, Ugo Blandin, Nicolas Bourdaud, Giulio Campanaro, Gil Cardoso, Nathanael Cottet, Charlotte Cullip, Samuel Deléglise, Louise Devanz, Adam Devulder, Antoine Essig, Pierre Février, Adrien Gicquel, Élie Gouzien, Antoine Gras, Jérémie Guillaud, Efe Gümüş, Mattis Hallén, Anissa Jacob, Paul Magnard, Antoine Marquet, Salim Miklass, Théau Peronnin, Stéphane Polis, Felix Rautschke, Ulysse Réglade, Julien Roul, Jeremy Stevens, Jeanne Solard, Alexandre Thomas, Jean-Loup Ville, Pierre Wan-Fat, Raphaël Lescanne, Zaki Leghtas, Joachim Cohen, Sébastien Jezouin, Anil Murani,
• Abstract summary: Cat-qubits are a promising architecture for quantum processors due to their built-in quantum error correction. We show a 160-fold improvement in bit-flip time compared to a standard cat. We also demonstrate a two-fold reduction in $Z$-gate infidelity.
• Score: 22.42362976537419
• License:
• Abstract: Dissipative cat-qubits are a promising architecture for quantum processors due to their built-in quantum error correction. By leveraging two-photon stabilization, they achieve an exponentially suppressed bit-flip error rate as the distance in phase-space between their basis states increases, incurring only a linear increase in phase-flip rate. This property substantially reduces the number of qubits required for fault-tolerant quantum computation. Here, we implement a squeezing deformation of the cat qubit basis states, further extending the bit-flip time while minimally affecting the phase-flip rate. We demonstrate a steep reduction in the bit-flip error rate with increasing mean photon number, characterized by a scaling exponent $\gamma=4.3$, rising by a factor of 74 per added photon. Specifically, we measure bit-flip times of 22 seconds for a phase-flip time of 1.3 $\mu$s in a squeezed cat qubit with an average photon number $\bar{n}=4.1$, a 160-fold improvement in bit-flip time compared to a standard cat. Moreover, we demonstrate a two-fold reduction in $Z$-gate infidelity, with an estimated phase-flip probability of $\epsilon_X = 0.085$ and a bit-flip probability of $\epsilon_Z = 2.65 \cdot 10^{-9}$ which confirms the gate bias-preserving property. This simple yet effective technique enhances cat qubit performances without requiring design modification, moving multi-cat architectures closer to fault-tolerant quantum computation.

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