Lecturer: Dr. Rajamani Vijayaraghavan
Affiliation: Tata Institute of Fundamental Research, Mumbai
Abstract:
Recent progress in ultra-low noise
amplification techniques using
superconducting devices has enabled fast and
high-fidelity measurements of solid-state
quantum devices. In this talk, I will focus on
superconducting circuits which are engineered
to behave like ‘artificial atoms’ when operated
at dilution temperatures (~ 10 mK).
These circuits have quantized energy levels
which can be manipulated and measured using
microwave frequency signals. We treat the two
lowest quantum levels of the circuit as a
quantum bit or qubit. The measurement signal
is amplified using a near-noiseless
superconducting parametric amplifier enabling
high-fidelity monitoring of the quantum state.
This paves the way to develop feedback
protocols to prepare and stabilize various kinds
of quantum states in these circuits. I will focus
on the measurement architecture in
superconducting circuits and describe how one
can implement a near ideal quantum
measurement setup. I will describe how we can
control the strength of a quantum
measurement in this architecture and discuss
the information obtained in weak quantum
measurements. Finally, I will discuss different
feedback protocols and their applications for
quantum information processing.