Ancilla assisted measurements on quantum ensembles: General protocols and applications in NMR quantum information processing

TL;DR

This paper reviews recent protocols for measurements in quantum ensembles using ancillary systems, demonstrating their experimental implementation via NMR techniques for applications like state characterization and noise engineering.

Contribution

It introduces general protocols for ancilla-assisted measurements in quantum ensembles and showcases their experimental realization in NMR quantum information processing.

Findings

Demonstrated noninvasive measurement techniques

Extracted expectation values of various operators

Characterized quantum states and processes

Abstract

Quantum ensembles form easily accessible architectures for studying various phenomena in quantum physics, quantum information science, and spectroscopy. Here we review some recent protocols for measurements in quantum ensembles by utilizing ancillary systems. We also illustrate these protocols experimentally via nuclear magnetic resonance techniques. In particular, we shall review noninvasive measurements, extracting expectation values of various operators, characterizations of quantum states, and quantum processes, and finally quantum noise engineering.