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Related Experiment Video

Updated: Jun 18, 2025

Generation and Coherent Control of Pulsed Quantum Frequency Combs

Generation and Coherent Control of Pulsed Quantum Frequency Combs

Published on: June 8, 2018

Reversing Unknown Quantum Processes via Virtual Combs for Channels with Limited Information.

Chengkai Zhu¹, Yin Mo¹, Yu-Ao Chen¹

¹Thrust of Artificial Intelligence, Information Hub, <a href="https://ror.org/00q4vv597">The Hong Kong University of Science and Technology (Guangzhou)</a>, Guangzhou 511453, China.

Physical Review Letters

|August 2, 2024

Summary

This study introduces virtual combs, a novel framework for reversing unknown quantum processes. This method enables exact inversion of specific quantum channels and unitary operations, overcoming inherent quantum irreversibility.

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Area of Science:

Quantum Information Science
Quantum Dynamics
Quantum Process Tomography

Background:

Open quantum systems exhibit inherent irreversibility, hindering the inversion of unknown quantum processes.
Accurate characterization and reversal of quantum operations are crucial for quantum computing and communication.

Purpose of the Study:

To develop a novel framework, virtual combs, for inverting unknown quantum processes.
To demonstrate the capability of virtual combs in exactly and approximately reversing various quantum channels and operations.

Main Methods:

The proposed framework, virtual combs, iteratively probes the unknown quantum process.
Classical postprocessing is employed to simulate the inverse of the quantum process.
Analysis of the error decay for approximate inversion and the trade-off between slots and sampling overhead.

Main Results:

An n-slot virtual comb can exactly reverse a depolarizing channel with one unknown parameter.
A 1-slot virtual comb achieves exact reversal for arbitrary pairs of quantum channels.
Approximate inversion exhibits a worst-case error decay of O(n^{-1}) for depolarizing channels.
Virtual combs universally reverse unitary operations.

Conclusions:

Virtual combs offer a powerful and versatile approach to overcoming the irreversibility of quantum dynamics.
The framework provides exact and approximate solutions for inverting unknown quantum processes, with tunable performance based on the number of slots.
This work advances quantum process characterization and has implications for quantum technologies.