This research deals with a recently proposed scheme for producing and detecting quantum states of an opto-mechanical system. The scheme is based on nested-interferometers and quantum post-selection techniques. Consider a photon entering a Mach-Zender interferometer. The photon encounters an optomechanical system in one arm of the Mach-Zender interferometer. If the photon does not succeed in changing the phonon excitation of the optomechanical system the photon will leave the interferometer in one specific output of the interferometer. However in the rare event of a phonon excitation the photon can leave the interferometer at the second output of the interferometer. Photon detection in this second output will post-select for a strong optomechanical interaction. Combining this with a second interferometry method for the same photon, based on optical delay lines, can yield information on the decoherence of the optomechanical system. This method relieves several of the challenges associated with previous optical schemes for measuring macroscopic superpositions, and only requires the devices to be in the weak coupling regime. With the implementation of this new scheme combined with advances in the design and fabrication of optomechanical systems (based on the use of Graphene, Silicon Nitride films, Boron Nitride and Carbon nanotube technology) it is expected that significant progress towards testing quantum mechanics at the macroscopic scale can be made.
Photons take a quantum Mulligan
Imagine a game of golf in which you are allowed millions of do-overs, so-called "Mulligans," until finally hitting that hole-in-one. This research on "Quantum Post Selected Optomechanics" aims precisely at doing this. Since the famous Schrödinger's Cat thought experiment, physicists have tried to observe quantum effects in larger and larger systems, in order to better understand the transition from quantum to classical behavior. In particular, interest has focused on optomechanical systems, tiny mechanical devices that can be pushed by light. However, it has proven extremely difficult to design a so-called "strongly coupled" device, one that is flimsy enough to be pushed significantly by a single photon. This research deals with a way to send many individual photons and then, after the fact, pick only those hole-in-one events where, thanks to a quantum fluctuation, the push was significant. After the interaction with the mechanical device, the photon interferes with itself, and usually travels one way. It only travels the other way if it has actually given a quantum of motion to the device (a hole-in-one). This method of post-selection should enable the study of quantum dynamics of mechanical systems.
