Noise-Canceling Quantum Feedback: non-Hermitian Dynamics with Applications to State Preparation and Magic State Distillation

• URL: http://arxiv.org/abs/2507.05611v1
• Date: Tue, 08 Jul 2025 02:43:32 GMT
• Title: Noise-Canceling Quantum Feedback: non-Hermitian Dynamics with Applications to State Preparation and Magic State Distillation
• Authors: Tathagata Karmakar, Philippe Lewalle, Yipei Zhang, K. Birgitta Whaley,
• Abstract summary: Time-continuous quantum measurement allows for the tracking of a quantum system in real time via sequences of short, and individually weak, measurement intervals.<n>We consider diffusive quantum trajectories, and focus on the "noise-canceling" subset of feedback protocols.<n>We derive such a class of feedback operations, showing that under the idealized assumptions of pure states, unit measurement efficiency, and zero time-delay in implementing feedback operations, perfectly noise-canceling feedback always exists.
• Score: 0.6749750044497732
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Time-continuous quantum measurement allows for the tracking of a quantum system in real time via sequences of short, and individually weak, measurement intervals. Such measurements are necessarily invasive, imparting backaction to the system, and allowing the observer to update their state estimate based on stochastic measurement outcomes. Feedback control then involves real-time interventions by an observer, conditioned on the time-continuous measurement signal that they receive. We here consider diffusive quantum trajectories, and focus on the "noise-canceling" subset of feedback protocols that aim to minimize the degree of stochasticity in the dynamics. We derive such a class of feedback operations, showing that under the idealized assumptions of pure states, unit measurement efficiency, and zero time-delay in implementing feedback operations, perfectly noise-canceling feedback always exists. We consider the resulting noise-canceled dynamics generated by an effective non-Hermitian Hamiltonian; while non-Hermitian Hamiltonians from continuous monitoring generally describe rare dynamics (accessible by costly post-selection), the use of noise-canceling feedback here leads to non-Hermitian dynamics that occur deterministically. We demonstrate this via examples of entangled state preparation and stabilization. We then illustrate the potential for the application of noise-cancellation to boost success rates in magic state distillation protocols. We show that adding feedback based on noise-cancellation into a time-continuous 5-to-1 distillation protocol leads to higher probabilities of successful distillation across a range of input errors, and extends the threshold on input errors for which the protocol is effective. Our results highlight the efficacy of noise-canceling feedback-aided protocols for quantum state preparation and stabilization tasks.

Related papers

• Quantum sensing of displacements with stabilized GKP states [41.94295877935867]
  We show how protocols for the stabilization of Gottesman-Kitaev-Preskill states can be used for the estimation of two-quadrature displacement sensing.<n>Thanks to the stabilization, this sensor is backaction evading and can function continuously without reset, making it well suited for the detection of itinerant signals.
  arXiv  Detail & Related papers  (2025-06-25T17:18:50Z)
• Error mitigation of shot-to-shot fluctuations in analog quantum simulators [46.54051337735883]
  We introduce an error mitigation technique that addresses shot-to-shot fluctuations in the parameters for the Hamiltonian governing the system dynamics.<n>We rigorously prove that amplifying this shot-to-shot noise and extrapolating to the zero-noise limit recovers noiseless results for realistic noise distributions.<n> Numerically, we predict a significant enhancement in the effective many-body coherence time for Rydberg atom arrays under realistic conditions.
  arXiv  Detail & Related papers  (2025-06-19T18:00:00Z)
• Enhancing Revivals Via Projective Measurements in a Quantum Scarred System [51.3422222472898]
  Quantum many-body scarred systems exhibit atypical dynamical behavior, evading thermalization and featuring periodic state revivals.<n>We investigate the impact of projective measurements on the dynamics in the scar subspace for the paradigmatic PXP model.<n>We identify a measurement-induced phase resynchronization, countering the natural dephasing of quantum scars, as the key mechanism underlying this phenomenon.
  arXiv  Detail & Related papers  (2025-03-28T17:03:14Z)
• Bayesian Quantum Amplitude Estimation [49.1574468325115]
  We introduce BAE, a noise-aware Bayesian algorithm for quantum amplitude estimation.<n>We show that BAE achieves Heisenberg-limited estimation and benchmark it against other approaches.
  arXiv  Detail & Related papers  (2024-12-05T18:09:41Z)
• Verification of entangled states under noisy measurements [3.8094794637714027]
  Entanglement plays an indispensable role in numerous quantum information and quantum computation tasks.<n>In recent years, quantum state verification has received increasing attention, yet the challenge of addressing noise effects in implementing this approach remains unsolved.<n>We provide a systematic assessment of the performance of quantum state verification protocols in the presence of measurement noise.
  arXiv  Detail & Related papers  (2024-06-03T15:59:02Z)
• Physics-informed tracking of qubit fluctuations [22.798654837751112]
  We implement a physics-informed and an adaptive Bayesian estimation strategy and apply them in real time to a semiconductor spin qubit. The strategy propagates a probability distribution inside the quantum controller according to the Fokker-Planck equation. The strategy can be applied to other qubit platforms by tailoring the appropriate update equation to capture their distinct noise sources.
  arXiv  Detail & Related papers  (2024-04-14T10:41:48Z)
• Lindblad-like quantum tomography for non-Markovian quantum dynamical maps [46.350147604946095]
  We introduce Lindblad-like quantum tomography (L$ell$QT) as a quantum characterization technique of time-correlated noise in quantum information processors.<n>We discuss L$ell$QT for the dephasing dynamics of single qubits in detail, which allows for a neat understanding of the importance of including multiple snapshots of the quantum evolution in the likelihood function.
  arXiv  Detail & Related papers  (2024-03-28T19:29:12Z)
• Noisy atomic magnetometry with Kalman filtering and measurement-based feedback [0.0]
  We propose a comprehensive approach that integrates measurement, estimation and control strategies.<n>This involves implementing a quantum non-demolition measurement based on continuous light-probing of the atomic ensemble.<n>Thanks to the feedback proposed, the atoms exhibit entanglement even when the measurement data is discarded.
  arXiv  Detail & Related papers  (2024-03-21T18:11:09Z)
• Quantum state preparation via engineered ancilla resetting [0.0]
  We study a protocol that incorporates periodic quantum resetting to prepare ground states of frustration-free parent Hamiltonians. This protocol uses a steering Hamiltonian that enables local coupling between the system and ancillary degrees of freedom. Our numerical results show that ancilla system entanglement is essential for faster convergence.
  arXiv  Detail & Related papers  (2023-05-15T13:34:07Z)
• Assessment of weak-coupling approximations on a driven two-level system under dissipation [58.720142291102135]
  We study a driven qubit through the numerically exact and non-perturbative method known as the Liouville-von equation with dissipation. We propose a metric that may be used in experiments to map the regime of validity of the Lindblad equation in predicting the steady state of the driven qubit.
  arXiv  Detail & Related papers  (2020-11-11T22:45:57Z)
• Time-delayed quantum feedback and incomplete decoherence suppression with no-knowledge measurement [0.0]
  The no-knowledge quantum feedback was proposed as a measurement-based feedback protocol for decoherence suppression for an open quantum system. We generalize the original work by analyzing non-Markovian average dynamics. We find that, when the qubit's unitary dynamics does not commute with the measurement and feedback controls, the decoherence rate can be either suppressed or amplified, depending on the delay time.
  arXiv  Detail & Related papers  (2020-10-14T09:32:24Z)
• Quantum Zeno effect appears in stages [64.41511459132334]
  In the quantum Zeno effect, quantum measurements can block the coherent oscillation of a two level system by freezing its state to one of the measurement eigenstates. We show that the onset of the Zeno regime is marked by a $textitcascade of transitions$ in the system dynamics as the measurement strength is increased.
  arXiv  Detail & Related papers  (2020-03-23T18:17:36Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.