Programmable Superradiance in an Interacting Qubit Array

When multiple quantum emitters couple to a common environment, interference gives rise to superradiance and subradiance. We realize a superconducting qubit array with programmable collective dissipation and coherent interactions, enabling direct control and microscopic measurement of collective decay. Our work provides a platform for exploring these phenomena and their potential quantum information applications.

Entangling Superconducting Qubits via Energy-Selective Local Reservoirs

Dissipation is usually viewed as harmful to quantum systems, but when carefully engineered, it can become a resource for creating and protecting entanglement. We realized energy-selective local reservoirs for superconducting qubits and used them to autonomously stabilize two-qubit entangled states with fidelity up to 90.8%. This provides a hardware-efficient approach to dissipative preparation and control of correlated quantum states.

Probing Site-Resolved Current in Strongly Interacting Superconducting Circuit Lattices

We demonstrated site-resolved measurement of particle currents and their statistics in synthetic quantum matter realized with superconducting circuit lattices. By employing artificial particle reservoirs, we explored non-equilibrium quantum transport in strongly interacting 1D systems. Our approach offers a new microscopic perspective on the dynamics of quantum particles.

Tunneling Spectroscopy in Superconducting Circuit Lattices

We demonstrated tunneling spectroscopy of synthetic quantum matter formed by microwave photons in a superconducting circuit lattice—the first realization of this key condensed matter technique in an analog quantum simulator. By employing engineered particle baths as tunneling probes, our method directly measures lattice-site-resolved quasiparticle and quasihole spectra.

End-to-end workflow for machine learning-based qubit readout with QICK and hls4ml

We developed an accessible workflow to enhance superconducting qubit readout by integrating machine learning (ML) algorithms into quantum control hardware.

Dissipatively Stabilized Mott Insulator of Photons Nature 566, 51–57 (2019)
By using engineered dissipation to create a reservoir for photons, we realized a Mott insulator of photons in a Bose-Hubbard lattice where the photons self-organize into a “crystal“ due to strong quantum interactions. See also our theory paper on stabilizing a broad range of gapped, incompressible photonic phases: Phys. Rev. A 95, 043811 (2017).

Topological lattice for microwave photons Phys. Rev. A 97, 013818 (2018)
We created a lattice built from coupled arrays of 3D microwave cavities, in which the motion of the microwave photons mimics that of electrons in a magnetic field. We observed topologically protected chiral edge states. We further propose to realize fractional quantum Hall states of photons by incorporating superconducting qubits to mediate strong interactions in our topological photonic lattices: Phys. Rev. X 6, 041043 (2016).

Hamiltonian Tomography for Photonic Lattices
As we scale up our quantum simulator to larger lattice sizes, how can we efficiently characterize the parameters of the lattice, e.g. to control lattice disorder?

Here develop robust spectroscopic methods for extracting individual parameters and topological properties of photonic lattices. - Phys. Rev. A 95, 062120 (2017).

Previous research: ultracold atoms in optical lattices

We create and study strongly-correlated phases of ultracold atoms in optical lattices. Using our Quantum Gas Microscope, we can engineer, manipulate and detect these states with the ultimate single-site resolution.

Quantum gas microscope (Greiner Lab)

Single-site resolved images of Mott insulator shells in a trap - Science 329, 547-550 (2010)

Quantum magnetism in optical lattices: transition from a paramagnet to an anti-ferromagnet - Nature 472, 307-312 (2011)

Photon assisted tunneling: engineering lattice dynamics on demand - Phys. Rev. Lett. 107, 095301 (2011)

Bilayer quantum gases: engineered coupling between two 2D planes, and techniques for site-resolved imaging of bilayers, - Phys. Rev. A 91, 041602(R) (2015)

Direct measurement of entanglement entropy in an itinerant lattice, using many-body quantum interference. - Nature 528: 7783 (2015)