Brian Pepper

Optomechanical superpositions via nested interferometry.

We present a scheme for achieving macroscopic quantum superpositions in optomechanical systems by using single photon postselection and detecting them with nested interferometers. This method relieves many of the challenges associated with previous optical schemes for measuring macroscopic superpositions and only requires the devices to be in the weak coupling regime. It requires only small improvements on currently achievable device parameters and allows the observation of decoherence on a time scale unconstrained by the systems optical decay time. Prospects for observing novel decoherence mechanisms are discussed.

Optical side-band cooling of a low frequency optomechanical system

For experimental investigations of macroscopic quantum superpositions and the possible role of gravitational effects on the reduction of the corresponding quantum wave function it is beneficial to consider large mass, low frequency optomechanical systems. We report optical side-band cooling from room temperature for a 1.5×10⁻¹⁰ kg (mode mass), low frequency side-band resolved optomechanical system based on a 5 cm long Fabry-Perot cavity. By using high-quality Bragg mirrors for both the stationary and the micromechanical mirror we are able to construct an optomechanical cavity with an optical linewidth of 23 kHz. This, together with a resonator frequency of 315 kHz, makes the system operate firmly in the side-band resolved regime. With the presented optomechanical system parameters cooling close to the ground state is possible. This brings us one step closer to creating and verifying macroscopic quantum superpositions.

Optomechanical Micro-Macro Entanglement

We propose to create and detect optomechanical entanglement by storing one component of an entangled state of light in a mechanical resonator and then retrieving it. Using micro-macro entanglement of light as recently demonstrated experimentally, one can then create optomechanical entangled states where the components of the superposition are macroscopically different. We apply this general approach to two-mode squeezed states where one mode has undergone a large displacement. Based on an analysis of the relevant experimental imperfections, the scheme appears feasible with current technology.

Nested trampoline resonators for optomechanics

Two major challenges in the development of optomechanical devices are achieving a low mechanical and optical loss rate and vibration isolation from the environment. We address both issues by fabricating trampoline resonators made from low pressure chemical vapor deposition (LPCVD) Si

Macroscopic superpositions via nested interferometry: finite temperature and decoherence considerations

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Experimental exploration of the optomechanical attractor diagram and its dynamics

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Optical Cooling of a 122-kHz Mechanical Resonator

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Optomechanical trampoline resonators

with a distributed bragg reflector (DBR) mirror. We design a nested double resonator structure with 80 dB of mechanical isolation from the mounting surface at the inner resonator frequency, and we demonstrate up to 45 dB of isolation at lower frequencies in agreement with the design. We reliably fabricate devices with mechanical quality factors of around 400,000 at room temperature. In addition these devices were used to form optical cavities with finesse up to 181,000

Quantum Optomechanics in the Bistable Regime

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Postselected optomechanical superpositions

1,000. These promising parameters will enable experiments in the quantum regime with macroscopic mechanical resonators.