Regal Group Research

Laser cooling of atoms uses radiation forces of light to push on atoms, and has revolutionized atomic physics.  In our work, in a field known as optomechanics, we now have the capacity to cool vibrations of mesoscopic objects using radiation pressure combined with cryogenic cooling.  We pick out particular nanomechanical modes of the solid that are well-isolated from their environment, and that we can control with light using an extremely-precise optical cavity.

With this capability we explore long-predicted quantum limits to interferometric sensing, and apply control of mechanical degree of freedom to quantum information processing.  In our experiments, we work with mechanical drumlike membranes of SiN that oscillate at MHz frequencies.  With these membranes we observed quantum backaction in an interferometric measurement of mechanical motion, i.e. radiation pressure shot noise, on our membrane microresonators. This realization subsequently led to exploration of strong optomechanical squeezing of light, and the use of quantum correlations to improve displacement detection. 

We are now looking at the unique ramifications of cavity optomechanics and phononic-crystal membrane resonators for sensing.

Electro-optic devices are ubiquitous in classical optical systems.  In the quantum domain, an electro-optic device would also be very handy, for example, to transduce states created with superconducting quantum bits (qubits) to optical light.  However, at the moment no electro-optic component exists that is low enough noise and efficient enough to work with quantum states.  In collaboration with Konrad Lehnert's group (JILA) we believe the control of phonon modes that has been developed in optomechanics and electromechanics could provide the requisite quantum link between microwave and optical photons.  In our work a metallized silicon nitride membrane is simultaneously coupled to an electrical resonator and an optical cavity.  This system creates a device that we have demonstrated is uniquely bidirectional and efficient.  Our current work studies the potential for the transduction of quantum states with low added noise at cryogenic temperatures required for superconducting qubits.

We are building a new apparatus that will study large quantum systems of Rydberg atoms in optical tweezers harnessing a cryogenic, high-vacuum environment.  This work is collaboration with the Kaufman group at JILA.  Check back for more information!

We are studying a quantum system of bosonic ⁸⁷Rb atoms in optical tweezers assembled particle-by-particle.  We have shown optical tweezers can be used to confine atoms sufficiently to place them in their motional ground state via Raman sideband laser cooling.  With this ability, we make bosonic atoms indistinguishable in all but their positional degree of freedom, and we can interfer two atoms to see the analog of the Hong-Ou-Mandel effect with atoms.  Further, this capability has implications for neutral-atom control in a variety of optical tweezer experiments, such as those utilizing Rydberg blockade.  With full access to local observables, we have done some of the first work verifying spin entanglement of individual ground-state neutral atoms, and we have studied analogs to interference and entanglement with single photons using non-interacting bosonic atoms.  We have been fortunate to study our systems in collaboration with the theory group of Ana Maria Rey (JILA).