December 2021 Janet Das Sarma Memorial Conference
We are pleased to announce the 2021 Janet Das Sarma Memorial CMTC Conference, a scientific conference in memory of Janet Das Sarma, who played a crucial behind-the scene role in making the Condensed Matter Theory Center at the University of Maryland (www.physics.umd.edu/cmtc/) a success and profoundly affected all aspects of the center.
Photoexcitation of graphene in the quantum Hall regime
Dissertation Committee Chair: Prof. Mohammad Hafezi, Co-Advisor
Committee:
Dr. Glenn Solomon, Co-Advisor
Dr. Johnpierre Paglione
Dr. Jay Deep Sau
Dr. Thomas E. Murphy, Dean’s Representative
Abstract:
Observation of measurement-induced quantum phases in a trapped-ion quantum computer
Many-body open quantum systems balance internal dynamics against decoherence from interactions with an environment. In this talk, I describe an experiment that explores this balance via random quantum circuits implemented on a trapped-ion quantum computer, where the system evolution is represented by unitary gates with interspersed projective measurements. As the measurement rate is varied, a purification phase transition is predicted to emerge at a critical point akin to a fault-tolerant threshold.
Experimental simulation of para-particle dynamics
Quantum mechanics allows for a consistent formulation of particles that are neither bosons nor fermions. In this talk, I’ll present a particular example of those particles, the so-called para-particles, which arise as a generalization of the usual bosons and fermions. Even though these particles are unlikely to be present in nature, a quantum system involving a spin-½ degree of freedom coupled to two bosonic modes yields a Hamiltonian that describes para-bosons and para-fermions.
On the nature of the Josephson effect in topologically nontrivial materials
Dissertation Committee Chair: Prof. James Williams
Committee:
Prof. Alicia Kollàr
Prof. Johnpierre Paglione
Prof. Frederick Wellstood
Prof. Ichiro Takeuchi
Abstract:
ANALOGUE COSMOLOGY EXPERIMENTS WITH SODIUM BOSE EINSTEIN CONDENSATES
Dissertation Committee Chair:
Professor Steven Rolston (Chair)
Dr. Gretchen Campbell (Co-Chair)
Committee:
Professor Steven Rolston
Dr. Gretchen Campbell
Dr. Ian Spielman
Professor Mohammad Hafezi
Professor Rajarshi Roy
Abstract:
Sensing with optical and acoustic waves
In this seminar, I will discuss several recent and ongoing experimental efforts in the Purdy Lab (which specializes in quantum sensors and transducers with optical, mechanical, and microwave systems), with a focus on some often overlooked or least under-appreciated aspects of relatively simple measurements. We have recently completed the first detailed study of acoustic blackbody radiation interacting with a nanomechanical system. While the acoustic equivalent of the well-known electromagnetic blackbody radiation should be equally ubiquitous, there have been almost no experiment
Nonequilibrium phases of matter on NISQ hardware
Recent progress on noisy, intermediate scale quantum (NISQ) devices opens exciting opportunities for many-body physics. NISQ platforms are indeed not just computers, but also interesting laboratory systems in their own right, offering access to large Hilbert spaces with exceptional capabilities for control and measurement. I will argue that nonequilibrium phases in periodically-driven (Floquet) systems are a particularly good fit for such capabilities in the near term.
Classification of (2+1)D invertible fermionic topological phases with symmetry
The integer quantum Hall states, the quantum spin Hall insulator, and the (2+1)D p-wave topological superconductor each have an important place in condensed matter physics due to their quantized symmetry-protected topological invariants. These systems have a unique ground state on any closed manifold in (2+1) dimensions, and are examples of 'invertible' topological phases of fermions. Here I will describe a general theory which fully encodes the universal properties of such invertible phases, and classifies them based on their symmetries.
Large-N solvable models of measurement-induced criticality
Competition between unitary dynamics that scrambles quantum information non-locally and local measurements that probe and collapse the quantum state can result in a measurement-induced entanglement phase transition. Here we introduce analytically tractable models of measurement-induced criticality in large-N Brownian hybrid circuit model composed of qubits [1]. The system is initially entangled with an equal sized reference, and the subsequent hybrid system dynamics either partially preserves or totally destroys this entanglement depending on the measurement rate.