Seminar

Abstract: This talk will review our recent work on classical and quantum glasses. I will start with a discussion of spin glasses from the perspective of chaos theory.

Error-correction is key to building a quantum computer. This includes both storage of quantum information as well as computing on it. Quantum low- density parity check (LDPC) codes offer a route to build these devices with low space overhead. The next question is - how do we fault-tolerantly com- pute on these codes?  Existing proposals (Cohen et al. [2110.10794], Cross et al. [2407.18393]) rely on ancilla systems appended to the original LDPC code.

Characterizing higher-order interactions in quantum processes with unknown Hamiltonians presents a significant challenge. This challenge arises, in part, because two-body interactions can lead to an arbitrary evolution, and two-local gates are considered universal in quantum computing. However, recent research has demonstrated that when the unknown Hamiltonian follows a U(1) symmetry, like charge or number conservation, N-body interactions display a distinct and symmetry-protected feature called the N-body phase.

Dr. Dripto Debroy will share his journey to becoming a research scientist at Google Quantum AI and offer tips for breaking into the tech industry.

Following this, he will present a research talk on his latest work for those interested.

*We strongly encourage attendees to use their full name (and if possible, their UMD credentials) to join the zoom session.*

Quantum sensing extends the vast benefits of a quantum advantage to traditional metrology.  A common method of quantum sensing utilizes coherent, crystal defects in semi-conductors (such as nitrogen vacancy centers in diamond) to perform high-precision measurements on a variety of length scales.  Such measurements might span from vectorized magnetometry of macroscopic computer chips to nanoscale strain or temperature mapping in a target matrial.  In exploring new regimes for quantum sensing, we need to model and assess their viability through theoretical or simula

Join us for a virtual panel featuring four current postdocs as they share their experiences applying for, securing, and thriving in postdoctoral positions. Gain valuable insights into crafting compelling applications, navigating the interview process, and making the most of your postdoc experience. Whether you're preparing for a postdoc or simply exploring your options, this discussion will provide practical advice and answer your questions. 

We analyse the entanglement structure of states generated by random constant-depth two-dimensional quantum circuits, followed by projective measurements of a subset of sites. By deriving a rigorous lower bound on the average entanglement entropy of such post-measurement states, we prove that macroscopic long-ranged entanglement is generated above some constant critical depth in several natural classes of circuit architectures, which include brickwork circuits and random holographic tensor networks.

Arrays of gate-defined semiconductor quantum dots are among the leading candidates for building scalable quantum processors.  High-fidelity initialization, control, and readout of spin qubit registers require exquisite and targeted control over key Hamiltonian parameters that define the electrostatic environment.  However, due to the tight gate pitch, capacitive crosstalk between gates hinders independent tuning of chemical potentials and interdot couplings.  While virtual gates offer a practical solution, determining all the required cross-capacitance matrices accurate

The title and abstract for this talk are forthcoming.

*We strongly encourage attendees to use their full name (and if possible, their UMD credentials) to join the zoom session.*

Between NISQ (noisy intermediate scale quantum) approaches without any proof of robust quantum advantage and fully fault-tolerant quantum computation, we propose a scheme to achieve a provable superpolynomial quantum advantage (under some widely accepted complexity conjectures) that is robust to noise with minimal error correction requirements. We choose a class of sampling problems with commuting gates known as sparse IQP (Instantaneous Quantum Polynomial-time) circuits and we ensure its fault-tolerant implementation by introducing the tetrahelix code.