Combined Dissipative and Hamiltonian Confinement of Cat Qubits

Autor: Ronan Gautier, Alain Sarlette, Mazyar Mirrahimi
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: PRX Quantum, Vol 3, Iss 2, p 020339 (2022)
Druh dokumentu: article
ISSN: 2691-3399
DOI: 10.1103/PRXQuantum.3.020339
Popis: Quantum error correction with biased-noise qubits can drastically reduce the hardware overhead for universal and fault-tolerant quantum computation. Cat qubits are a promising realization of biased-noise qubits as they feature an exponential error bias inherited from their nonlocal encoding in the phase space of a quantum harmonic oscillator. To confine the state of an oscillator to the cat-qubit manifold, two main approaches have been considered so far: a Kerr-based Hamiltonian confinement with high gate performances, and a dissipative confinement with robust protection against a broad range of noise mechanisms. We introduce a new combined dissipative and Hamiltonian confinement scheme based on two-photon dissipation together with a two-photon exchange (TPE) Hamiltonian. The TPE Hamiltonian is similar to Kerr nonlinearity, but unlike the Kerr it induces only a bounded distinction between even- and odd-photon eigenstates, a highly beneficial feature for protecting the cat qubits with dissipative mechanisms. Using this combined confinement scheme, we demonstrate fast and bias-preserving gates with drastically improved performance compared to dissipative or Hamiltonian schemes. In addition, this combined scheme can be implemented experimentally with only minor modifications of existing dissipative cat-qubit experiments.
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