Heat transport through a qubit under continuous quantum measurement

When one measures a quantum system, its state changes instantaneously. This backaction of quantum measurement comes from quantum mechanics, which does not appear in classical systems. In particular, in quantum many-body systems, it is known that the quantum measurements induce interesting phenomena, e.g., measurement-induced phase transition, suppression of the Kondo effect, and non-Hermitian dynamics. Furthermore, recent developments in experimental techniques have enabled us to observe the backaction of quantum measurements in well-controllable experimental systems, attracting more attention.

Since transport phenomena through a small quantum system strongly reflect the quantum state of the system, continuous quantum measurement to the system may change transport properties drastically. One of the simplest transport phenomena is heat transport through a qubit. Although it is simple, it is known that it exhibits abundant many-body phenomena, e.g., the Kondo effect and quantum phase transition due to the coupling with the heat bath. In addition, recent developments in superconducting-circuit technology have made it possible to measure heat current with high accuracy.

In this talk, we consider heat transport through a qubit under continuous quantum measurement and show how the heat current is affected by continuous quantum measurements onto the eigenstates of the qubit.