JQI Seminar

Abstract: Understanding the Hubbard model is crucial for investigating various quantum many-body states and its fermionic and bosonic versions have been largely realized separately. Recently, transition metal dichalcogenides heterobilayers have emerged as a promising platform for simulating the rich physics of the Hubbard model. In this work, we explore the interplay between fermionic and bosonic populations, using a WS₂/WSe₂ heterobilayer device that hosts this hybrid particle density.

Abstract: Superconducting circuits are an attractive system for forming qubits in a quantum computer because of the natural energy gap to excitations in the superconductor. However, experimentally it is observed that superconducting qubits have excitations above the superconducting ground state, known as quasiparticles, at a density that is many orders of magnitude above the expected equilibrium level.

Abstract: Over the last decade, flat optical elements composed of an array of deep-subwavelength dielectric or metallic nanostructures of nanoscale thicknesses – referred to as metasurfaces – have revolutionized the field of optics. Because of their ability to impart an arbitrary phase, polarization or amplitude modulation to an optical wavefront as well as perform multiple optical transformations simultaneously on the incoming light, they promise to replace traditional bulk optics in applications requiring compactness, integration and/or multiplexing.

Abstract: Arrays of neutral atoms promise to enable a variety of experiments across quantum science, including quantum information processing, metrology, and many-body physics. While there have been recent significant improvements in quantum control, coherence times, and entanglement generation, one outstanding limitation is the efficient implementation of dissipation or measurement.

Abstract: Faint states of light occur in multiple contexts, from fundamental physics to quantum information science to remote sensing and biology. At the same time, faint light naturally lends itself to optical quantum measurements. Such measurements not only enable detecting and using quantum properties of light such as entanglement and antibunching - but they also become a tool to observe and quantify quantum processes inside faint light sources.

Abstract:
JQI Seminars are held on Mondays during Fall and Spring semesters at 11:00 a.m. Eastern Time in Room 2400 of the Atlantic Building. University of Maryland affiliates may participate using Zoom. The seminars are also livestreamed on the JQI YouTube channel (https://www.youtube.com/user/JQInews), which supports audience participation in the chat interface.

Abstract: This talk will present our recent work on the use of arrays of Rydberg atoms to study quantum magnetism and to generate entangled states useful for quantum metrology. We rely on laser-cooled ensembles of up to hundred individual atoms trapped in microscopic optical tweezer arrays. By exciting the atoms into Rydberg states, we make them interact by the resonant dipole interaction. The system thus implements the XY spin ½ model, which exhibits various magnetic orders depending on the ferromagnetic or antiferromagnetic nature of the interaction.

Abstract: Enhancing the light-matter coupling in cavities provides an intriguing route to control properties of matter, from chemical reactions to transport and thermodynamic phase transitions. Order parameters which couple linearly to the electromagnetic field, such as ferroelectricity, incommensurate charge density waves, or exciton condensates, appear most suitable in this context, but the possible mechanisms are not well understood in many cases.

Abstract: Josephson junction-based microwave parametric amplifiers are ubiquitous in quantum computing research based on superconducting circuits. However, they still leave a lot to be desired when it comes to scaling up to the massive channel counts that many in the field are proposing. In this talk, I'll discuss an effort in our group to produce a new generation of parametric amplifiers that integrate quantum-limited noise performance with nonreciprocal signal routing.

Abstract: While it can be useful in some cases to abstract away all but 2 levels of the atoms used for quantum computing, it should not be forgotten that these qubit hosts often have many levels capable of participating in processing tasks.  These include long-lived states within hyperfine, Zeeman, and electronic-state structure in atoms, but extend to rotational, vibrational, and more exotic level landscapes if one considers molecules instead of just atoms.  Given the effectively atom-limited regime in which many (possibly all) atomic processors currently operate,