The nonclassical interference of multiple photons in an optical network plays a key role in a variety of applications ranging from quantum computing over quantum communication to quantum sensing.
However, the inability to generate identical photons is generally perceived as a strong drawback in the development of “real world” quantum optics technologies.
New research led by Dr Vincenzo Tamma, leader of the Quantum Optics and Quantum Information group, at the University of Portsmouth, has demonstrated for the first time that it is possible to “zoom” into the symmetric spectral properties of an arbitrary number N of interfering nonidentical photons in an arbitrary linear optical circuit. These results have been recently published in Physical Review A.
The differences in the photonic spectra become now a resource to exploit when one takes advantage of the full the multiphoton interference “quantum alphabet” encoded in the photonic parameters, such as time and frequency, recorded at the output of the optical network.
The good news is that the advent of detectors with unprecedented time- or frequency-resolution make this now feasible within the current technology.
These findings have the potential to develop novel future techniques for high-precision quantum sensing and quantum computational speed-up which take full advantage of the quantum information encoded in multiphoton interference with “real world” photonic sources.
Thanks to a collaboration with the group of Professor Pan at the Hefei National Laboratory for Physical Sciences, China, the predicted symmetric properties of multiphoton networks have been experimentally verified for N=3 interfering photons of different colours, as reported in Physical Review Letters.
Dr Tamma and his student Simon Laibacher have also shown in Physical Review A that an entire family of entangled (nonlocal correlated) states can be revealed by performing time-resolved or frequency-resolved correlation measurements even by using nonidentical photons and a fixed optical network. This has recently triggered experiments to observe the predicted entanglement landscapes.
Dr Tamma said: “These findings have the potential to develop novel future techniques for high-precision quantum sensing and quantum computational speed-up which take full advantage of the quantum information encoded in multiphoton interference with “real world” photonic sources.”