Seminar Schedule

During the last ten years, a fast-growing scientific activity has been devoted to understanding, controlling and using the dynamical degrees of freedom of levitated solid-state objects in vacuum. Levitated nanoparticles can move, rotate and fall. They also have solid-state internal degrees of freedom. At the interface between the fields of cavity optomechanics and atomic and molecular optics, the rich physics of levitated nanoparticles provide unique opportunities for applied and fundamental research. In this talk, we will first motivate and review the research activities in this field. We will then focus on two recent results in our theory group. First, we will discuss how the center-of-mass motion of a micromagnet can be coupled to its internal acoustic phononic modes. This offers a new cooling method and a tool to probe and control the internal physics of an isolated micromagnet. Then, we will discuss how to optimally control the harmonic potential of a levitated nanoparticle to quantum-delocalize its center-of-mass motional state. This has applications for testing quantum mechanics at large scales, enhancing sensitivities of force sensors, and boosting the entangling rate of two weakly interacting nanoparticles.

Circuit quantum electrodynamics, in which microwave cavity modes are coupled to “artificial atoms” realized with Josephson junction qubits, has allowed for a variety of investigations in quantum optics and quantum information. In recent years, our team at Yale has focused on a hardware efficient approach, where high-Q microwave cavities serve as quantum memories. When dispersively coupled to transmon qubits, quite complex non-classical states can be created in these cavities, and operations between cavities can be enacted through parametric driving or other means. For instance, we have recently shown high-quality cavity-cavity swaps via a beam-splitter or conversion operation, single and two-mode squeezing, and engineered cross and self Kerr interactions. Finally, one can perform strong projective measurements of the photon number, the photon parity, or indeed any other binary-valued operator within the multi-dimensional Hilbert space. This system therefore has all of capabilities of linear optical systems, but with the addition of deterministic state preparation, measurement, and nonlinear interactions. One way to employ these capabilities is to directly simulate problems which are “naturally” bosonic in nature, to calculate vibronic spectra, Franck-Condon factors, or nonlinear molecular dynamics. I will present preliminary work towards using this platform as a novel but programmable simulator for small molecules.

Rydberg atoms has emerged as a versatile platform for different applications in quantum technology from computing and simulation to sensing and imaging [1]. In this talk, I will focus on one of the many Rydberg projects in Durham. In our Rydberg quantum optics experiment, we store optical photons in a cold atomic ensemble in the form of Rydberg polaritons. In recent work, we have looked at the potential of Rydberg polaritons in the context of quantum information. We show that Rydberg polaritons have a number of attractive features. In particular, the combined atomic and photonic character of the polariton [2] allows coherent mapping between static and flying qubits, the large dipole moments between Rydberg states enables fast single qubit rotations, and as the quantum information is shared amongst many atoms, there is an in-built robustness to atom loss [3]. Finally, the robustness of collectively-encoded Rydberg qubits to environmental noise is considered.

The Gamma Factory (GF) is an ambitious proposal developed as part of the CERN Physics Beyond Colliders program to operate the LHC as a novel kind of a light source that can produce up to ~10¹⁷ photons per second with energies of up to ~400 MeV. The key idea is to scatter laser photons off of partially stripped ultrarelativistic ions. The GF would enable a number of hitherto impossible experiments and can be thought of not only as a unique photon source, but also as a giant ion trap for precision physics. The first step in practical realization of the GF is a full-featured proof-of-principle experiment at the SPS that is currently being considered by CERN.