Experimental quantum decoherence control by dark states of the environment

• Published in: New journal of physics 2020-09, Vol.22 (9), p.93058
• Main Authors: Stárek, Robert, Mičuda, Michal, Straka, Ivo, Nováková, Martina, Dušek, Miloslav, Ježek, Miroslav, Fiurášek, Jaromír, Filip, Radim
• Format: Article
• Language: English
• Subjects: dark states; decoherence; linear quantum optics; photonics; Physics; quantum; Quantum theory; Qubits (quantum computing)
• ISSN: 1367-2630; 1367-2630
• DOI: 10.1088/1367-2630/abb47d

Coherent interaction of a quantum system with environment usually induces quantum decoherence. However, remarkably, in certain configurations the coherent system-environment coupling can be simultaneously explored to engineer a specific dark state of the environment that eliminates the decoherence. Here we report on experimental demonstration of such protocol for suppression of quantum decoherence by quantum decoherence itself. The protocol is based on indirect control of the environment via quantum measurements on quantum probes interacting with the environment prior to the system that should be protected. No direct manipulation with the environment is required to suppress the decoherence. In our proof-of-principle experiment, we demonstrate protection of a single qubit coupled to another single qubit. We implement the required quantum circuits with linear optics and single photons, which allows us to maintain very high degree of control and flexibility in the experiment. Our results clearly confirm the decoherence suppression achieved by the protocol and pave the way to its application to other physical platforms.