Optimizing the choice of spin-squeezed states for detecting and characterizing quantum processes
- Univ. of Toronto, Toronto, ON (Canada)
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Univ. of Toronto, Toronto, ON (Canada); Canadian Institute for Advanced Research, Toronto, ON (Canada)
Quantum metrology uses quantum states with no classical counterpart to measure a physical quantity with extraordinary sensitivity or precision. Most such schemes characterize a dynamical process by probing it with a specially designed quantum state. The success of such a scheme usually relies on the process belonging to a particular one-parameter family. If this assumption is violated, or if the goal is to measure more than one parameter, a different quantum state may perform better. In the most extreme case, we know nothing about the process and wish to learn everything. This requires quantum process tomography, which demands an informationally complete set of probe states. It is very convenient if this set is group covariant—i.e., each element is generated by applying an element of the quantum system’s natural symmetry group to a single fixed fiducial state. In this paper, we consider metrology with 2-photon (“biphoton”) states and report experimental studies of different states’ sensitivity to small, unknown collective SU(2) rotations [“SU(2) jitter”]. Maximally entangled N00N states are the most sensitive detectors of such a rotation, yet they are also among the worst at fully characterizing an a priori unknown process. We identify (and confirm experimentally) the best SU(2)-covariant set for process tomography; these states are all less entangled than the N00N state, and are characterized by the fact that they form a 2-design.
- Research Organization:
- Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC04-94AL85000
- OSTI ID:
- 1214237
- Journal Information:
- Physical Review. X, Vol. 4, Issue 4; ISSN 2160-3308
- Publisher:
- American Physical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Extremal quantum states and their Majorana constellations
|
journal | September 2015 |
Calibration of Quantum Sensors by Neural Networks
|
journal | December 2019 |
| Extremal quantum states and their Majorana constellations | text | January 2015 |
Similar Records
Connections of geometric measure of entanglement of pure symmetric states to quantum state estimation
Computing spin networks