By creating photon states with photon numbers of more than one, it is possible to make measurements with resolution beyond conventional limits. For example, in interferometric applications, the resolution improvement can scale like 1/N with properly prepared states, where N is the number of photons in the state. While interferometry and other applications would benefit from high-N photon states, their creation is a significant experimental challenge. Various production schemes have been proposed. These include arrangements where correlated pairs of photons made by parametric downconversion are combined with other correlated pairs, or with coherent laser pulses, or through the use of these pulses with photon-number resolving detectors. Another possible scheme combines the outputs of arrays of quantum dot-based single photon sources. A key trick to any of these schemes is to do the combination in such a way that the likelihood of creating the desired N-photon state is not so rare that it renders the method impractical. We are exploring these state preparation ideas, as well as the metrology of the states produced and then once produced, the use of those states for high accuracy measurements.

In addition to the advances of N-photon sources, photon-number-resolving detectors also offer new capabilities for measurement applications. We currently have in our lab one of the world's best photon-number-resolving detector and it has nearly 100% detection efficiency. That is a combination that offers much potential in improved measurements as well as fundamental tests of physics and quantum mechanics.

 

key words

Entanglement; Metrology; Quantum information; Quantum state; Single photon; Single photon detector; Single photon source;

Citizenship:  Open to U.S. citizens

Level:  Open to Postdoctoral applicants