Recovering Quantum Coherence of a Cavity Qubit Coupled to a Noisy Ancilla through Real-Time Feedback
arXiv:2403.02081 · doi:10.1103/PhysRevX.14.041056
Abstract
Decoherence in qubits, caused by their interaction with a noisy environment, poses a significant challenge to the development of reliable quantum processors. A prominent source of errors arises from noise in coupled ancillas, which can quickly spread to qubits. By actively monitoring these noisy ancillas, it is possible to not only identify qubit decoherence events but also to correct these errors in real time. This approach is particularly beneficial for bosonic qubits, where the interaction with ancillas is a dominant source of decoherence. In this work, we uncover the intricate dynamics of decoherence in a superconducting cavity qubit due to its interaction with a noisy transmon ancilla. By tracking the noisy ancilla trajectory and using real-time feedback, we successfully recover the lost coherence of the cavity qubit, achieving a fivefold increase in its pure dephasing time. Additionally, by detecting ancilla errors and converting them into erasures, we improve the pure dephasing time by more than an order of magnitude. These advances are essential for realizing long-lived cavity qubits with high-fidelity gates, and they pave the way for more efficient bosonic quantum error-correction codes.
arXiv comment16 pages, 10 figures, including appendices
References in corpus (44)
- Quantifying Coherence
- Suppressing quantum errors by scaling a surface code logical qubit
- Fluxonium: single Cooper pair circuit free of charge offsets
- The Flux Qubit Revisited to Enhance Coherence and Reproducibility
- New material platform for superconducting transmon qubits with coherence times exceeding 0.3 milliseconds
- The Kerr-Cat Qubit: Stabilization, Readout, and Gates
- Real-time quantum error correction beyond break-even
- Observing single quantum trajectories of a superconducting qubit
- Transmon qubit with relaxation time exceeding 0.5 milliseconds
- A quantum memory with near-millisecond coherence in circuit QED
- Realization of an Error-Correcting Surface Code with Superconducting Qubits
- Implementing a Universal Gate Set on a Logical Qubit Encoded in an Oscillator
- Demonstration of quantum error correction and universal gate set on a binomial bosonic logical qubit
- Exponential suppression of bit-flips in a qubit encoded in an oscillator
- Granular aluminum: A superconducting material for high impedance quantum circuits
- Fast and Unconditional All-Microwave Reset of a Superconducting Qubit
- Erasure conversion for fault-tolerant quantum computing in alkaline earth Rydberg atom arrays
- Ultrahigh Error Threshold for Surface Codes with Biased Noise
- Bosonic quantum error correction codes in superconducting quantum circuits
- Feedback control of a solid-state qubit using high-fidelity projective measurement
- Searching for Dark Matter with a Superconducting Qubit
- Beating the break-even point with a discrete-variable-encoded logical qubit
- Three-dimensional superconducting resonators at mK with the photon lifetime up to seconds
- Fast Universal Control of an Oscillator with Weak Dispersive Coupling to a Qubit
- Microwave-controlled generation of shaped single photons in circuit quantum electrodynamics
- Universal Control of an Oscillator with Dispersive Coupling to a Qubit
- Fault-tolerant detection of a quantum error
- Thresholds for topological codes in the presence of loss
- Suppression of photon shot noise dephasing in a tunable coupling superconducting qubit
- Quantum information processing with bosonic qubits in circuit QED
- Quantum control of bosonic modes with superconducting circuits
- Cavity Attenuators for Superconducting Qubits
- Superconducting cavity qubit with tens of milliseconds single-photon coherence time
- Error-corrected gates on an encoded qubit
- Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier
- A Very Small Logical Qubit
- Seamless high-Q microwave cavities for multimode circuit QED
- Erasure qubits: Overcoming the limit in superconducting circuits
- Dual-rail encoding with superconducting cavities
- Demonstrating a long-coherence dual-rail erasure qubit using tunable transmons
- Leakage detection for a transmon-based surface code
- Tailored XZZX codes for biased noise
- Conditional not displacement: fast multi-oscillator control with a single qubit
- Non-Markovian Effects of Two-Level Systems in a Niobium Coaxial Resonator with a Single-Photon Lifetime of 10 ms