Special Quantum Seminar | Utilizing Symmetries in Open Quantum Systems: Autonomous Error Correction and Metrology

Quantum systems are crucial to developing new technologies and studying fundamental science. However, current systems cannot be fully isolated from the environment, which can introduce detrimental noise effects that destroy useful quantum features in these open quantum systems. Nevertheless, in some circumstances it is possible to instead utilize the environment as a resource via symmetries. Although the implications of symmetries in Hamiltonian systems are well-understood, in open quantum systems the situation is more complex. In this talk, I will show how two classes of symmetry exist for open quantum systems, “weak” and “strong”, and I will demonstrate the utility of strong symmetries via two examples. First, I will identify connections between steady state phase transitions and autonomous error correction, a form of quantum error correction in which active measurement and feedback is no longer needed. Second, I will show how strong symmetries allow for the preparation of highly-entangled collective states known as spin-squeezed states, which can be experimentally realized in optical cavity systems for quantum-enhanced metrology.