Harvard Quantum Initiative Special Seminar
Friday, March 8
11:00 AM
Jefferson 256
Leigh Martin (Berkeley)
Quantum feedback for measurement and control
Many fundamental quantum limits arise from the inevitable disturbance caused by
measurement. This disturbance imposes a barrier to precision measurement with no classical
analog, but also provides a uniquely quantum mechanism for control. This talk explores
both of these aspects in the context of quantum feedback. First, we discuss experimental
results showing how feedback can take a measurement of phase to its fundamental limit. By
continuously and adaptively changing measurement basis during readout of a single-photon
signal, we enhance sensitivity over existing techniques and implement a canonical phase
measurement. Second, we present theoretical methods for state control based on measurement
back-action. We apply these methods to the task of entanglement generation and propose
potential future experiments, including some that should be extremely robust to loss.
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