The open quantum system and its control laid the foundation of quantum mechanical and quantum information theory. Due to the interaction with the environment, the evolution of practical quantum system should be described by a quantum channel, instead of a unitary evolution for a closed quantum system.

The experimental studies on the quantum channel will not only deepen our understanding of the quantum open system, but also improve our ability to control the evolution of a quantum system, which is beneficial for the researches on quantum information and quantum computation. Therefore, the realization of arbitrary operation on a quantum bit, i.e. the simulation of an arbitrary quantum channel, is of great significance.

Recently, a research team lead by Luyan Sun from Tsinghua University collaborates with Chang-Ling Zou from University of Science and Technology of China, realized the arbitrary quantum channel simulation for a single qubit in a superconducting quantum circuit, and realized the arbitrary operation on a quantum bit.

The experiments are based on a three-dimensional microwave cavity and a coupled superconducting transmon qubit, with the cavity serving as the target qubit and transmon serving as an ancillary qubit, the arbitrary repetitive quantum channel simulation on the photonic qubit is realized. I

t is worth mentioning that, they developed a novel experimental scheme to realize the open quantum system control, with only minimum quantum resources of a single ancillary qubit and the real-time quantum feedback technology. Such a scheme can also be generalized to a higher dimension to realize arbitrary qudit channel simulation, which still only requires only single ancillary qubit.

The demonstrated quantum channel simulation can deterministically simulate the quantum bit evolution in an arbitrary physical environment and generated arbitrary quantum mixed state, would play an important role in the future applications, including quantum computation and quantum simulation.

Research Report: "Experimental repetitive quantum channel simulation"

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