E6: Quantum Control of Few- to Many-Body Quantum Systems in an Optical Cavity

Lab room: Campbell LL104
Lab phone: (510) 664-4841

Building on our group's work on cavity opto-dynamics on E3 and many-body physics on E4 and E5, E6 plans to study cavity control of quantum few- and many-body systems. 

Post-MOT chamber bakeout (summer 2017)

Post-MOT chamber bakeout (summer 2017)

We are working with Rubidium and have built a 3D MOT loaded from a 2D MOT. From a polarization-gradient-cooled cloud, we load a small fraction of the atoms into an optical dipole trap, which then transports the atoms from the MOT chamber to a second vacuum chamber, where experiments will be performed. Transport is performed by translating the focus of the ODT laser using a focus-tunable lens.

Chamber with MOT and transport optics (summer 2018)

Chamber with MOT and transport optics (summer 2018)

The science chamber (currently under construction) will house a high finesse (very shiny) optical cavity in the near-concentric regime (the cavity length is almost twice the mirrors’ radius of curvature), supporting a Gaussian mode with a small (~10 um) waist at the center (where the atoms will be trapped). The small mode waist means that the electric field of each photon in the cavity will be very concentrated at the location of the atoms, and high finesse means that each photon will live in the cavity for a long time, interacting with the atoms repeatedly as it bounces back and forth between the mirrors. This will give a high cavity QED cooperativity, which characterizes the ratio of coherent dynamics to incoherent dynamics in our system. By exchanging real or virtual cavity photons, the atoms can interact with one another; thus the cavity naturally provides infinite-range or all-to-all interactions between atoms in the cavity.

Cavity/science chamber design (spring 2019): the cavity mirrors are shown in blue. A bucket window allows us to place an out-of-vacuum objective (shown in gray, above the cavity) 13mm away from the cavity center for ~1um-resolution addressing and imaging.

Cavity/science chamber design (spring 2019): the cavity mirrors are shown in blue. A bucket window allows us to place an out-of-vacuum objective (shown in gray, above the cavity) 13mm away from the cavity center for ~1um-resolution addressing and imaging.

The near-concentric cavity configuration allows us to achieve high cooperativity without limiting our transverse access to the atoms. We are designing a high NA addressing and imaging system to allow us to shine light on the atoms transversely. Adding spatial addressability to the cavity system enables us to turn the all-to-all coupling provided by the cavity “bus” into programmable finite-range interactions between different atoms.

Cartoon picture of system: few to many atoms in optical cavity, individually addressable from the side. Atoms interact via the exchange of cavity photons; photons leaking out of the cavity provide information about the atomic dynamics.

Cartoon picture of system: few to many atoms in optical cavity, individually addressable from the side. Atoms interact via the exchange of cavity photons; photons leaking out of the cavity provide information about the atomic dynamics.

Another exciting feature of a cavity QED system is the ability to study open quantum systems. We can use cavity-mediated interactions for Hamiltonian-engineering-type experiments, just looking at coherent dynamics, but we can also explore the physics that arises as a result of the dissipation in the system (the leakage of photons out of the cavity, which can be detected on a single-photon detector or homodyne/heterodyne detector). This could be used to continuously monitor system dynamics, herald the success of a particular interaction or state preparation scheme, or even perform feedback in response to the measurement result.

This flexible apparatus has a lot of exciting science in its future, and our team is seeking new members! Join PhD students Justin and Emma, postdoc Johannes, and undergrads Alec, Aron, and Rachel!

Justin, Johannes, Emma, Aron, Alec, Rachel

Justin, Johannes, Emma, Aron, Alec, Rachel