Publications Kseniia VODENKOVA

2026

K. Vodenkova, A. Pocklington, F. Yang, A. Lingenfelter, A. A. Clerk, H. Pichler Efficient Simulation of Nonreciprocal Many-body Physics via Quantum Feedback, (2026-09-02), arXiv:2609.02518 arXiv:2609.02518 (ID: 721682) Toggle Abstract
We present a scheme to efficiently simulate nonreciprocal many-body spin models using a non-Markovian open system. Our scheme utilizes a single quantum emitter coupled to a waveguide mode that is fed back to the same emitter after a time delay. With this coherent delayed feedback, an effective nonreciprocal interaction can be engineered, wherein the emitter at earlier times affects itself at later times, creating a scalable spin chain. We show that all the steady-state quantities of such spin models can be accessed through measurement of the emitter and the output field. Furthermore, using classical feedback that resets the emitter, quench dynamics from arbitrary product states can be simulated. We demonstrate striking features of nonreciprocal models, such as the Liouvillian skin effect, anomalous relaxation dynamics, and quasi-long-range order of output photons. Finally, we show that the proposal is amenable to experimental realization and robust to imperfections. Our work establishes a feasible way to scale up a nonreciprocal many-body system, and provides a new route towards generation of exotic states of light.

K. Vodenkova, H. Pichler Continuous Coherent Quantum Feedback with Time Delays: Tensor Network Solution, Phys. Rev. X 14 31043 (2024-09-09), http://dx.doi.org/10.1103/PhysRevX.14.031043 doi:10.1103/PhysRevX.14.031043 (ID: 721144) Toggle Abstract
In this paper we develop a novel method to solve problems involving quantum optical systems coupled to coherent quantum feedback loops featuring time delays. Our method is based on exact mappings of such non-Markovian problems to equivalent Markovian driven dissipative quantum many-body problems. In this work we show that the resulting Markovian quantum many-body problems can be solved (numerically) exactly and efficiently using tensor network methods for a series of paradigmatic examples, consisting of driven quantum systems coupled to waveguides at several distant points. In particular, we show that our method allows solving problems in so far inaccessible regimes, including problems with arbitrary long time delays and arbitrary numbers of excitations in the delay lines. We obtain solutions for the full real-time dynamics as well as the steady state in all these regimes. Finally, motivated by our results, we develop a novel mean-field approach, which allows us to find the solution semi-analytically and identify parameter regimes where this approximation is in excellent agreement with our exact tensor network results.