Seminar

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.

To solve problems of practical importance, quantum computers will likely need to incorporate quantum error correction, where a logical qubit is redundantly encoded in many noisy physical qubits. The large physical-qubit overhead typically associated with error correction motivates the search for more hardware-efficient approaches. To this end, in this talk I will describe our recent superconducting circuit experiment realizing a logical qubit memory via the concatenation of encoded bosonic cat qubits with an outer repetition code.

Quantum computing’s potential relies heavily on innovative software that bridges the gaps between algorithms, hardware, and system support, and between current capabilities and the future vision for the field.

 A Landau level (which is a flat band) forms only when a magnetic flux with non-zero total flux threads a system. In fact the degeneracy at the flat band is proportional to the flux. So no flat band can form when the magnetic flux averages to zero. We will discuss this and then show otherwise. This is relevant to time reversal symmetric systems that form flat bands such as magic-angle twisted bilayer graphene. In this talk the magic behind those systems will be revealed through the simplest model that gives rise to magical behaviour.

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.*