Seminar of the ICMP
Seminar of the ICMP
Quantum-limited detectors: the concept and many-body effects
Recently, a new experimentally-grounded tendency has appeared: to
consider certain types of quantum mesoscopic systems (such as quantum-point
contacts) as quantum-limited detector measuring quantum states of another
quantum systems (such as charge- and spin qubits). In the framework of such
ideology the physical interaction between these two subsystems of larger
quantum system plays two distinct roles: i) the influence of measured
subsystem on quantum detector (i.e. the output signal) and ii) the
decoherence of the measured subsystem which should be refered to as
detector's backaction on the former. Obviously, in the case of
superposition of measured system's quantum states, the acquisiton of
information about any of these states (by means of quantum detector signal)
cannot be faster than the measured system's superposition state
decoherence. The ratio of corresponded two rates (acquisition information
rate and decoherence rate) - defines the quantum detector's efficiency. In
my talk I'll highlight some principles behind the theory of quantum-limited
detectors and report on some interesting many-body interaction effects
which will be crucial for the quality of a broad class of prospective
quantum-limited detectors.
Couple of useful references:
[1] D. V. Averin and E. V. Sukhorukov, Phys. Rev. Lett. 95, 126803 (2005).
[2] G.Skorobagatko, A.Bruch, S.-V.Kusminskiy, A.Romito, "Interaction
effects on quantum-limited detectors",
arXiv:1609.07281 <https://arxiv.org/abs/1609.07281>