Seminar

The abstract for this dissertation defense is forthcoming.

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

Quantum computers have the theoretical potential to solve problems intractable for classical computers. However, realizing this potential requires dealing with the noise inherent in near and far-term devices. One way of doing this is to redundantly encode the quantum information in a quantum error-correcting code and manipulate the encoded states to do computation. Protecting quantum information in this way incurs additional space overhead in the form of extra qubits; this is problematic since qubits are a scarce resource, especially for near-term quantum computers.

The abstract for this dissertation defense is forthcoming.

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

Instabilities, where initially small fluctuations seed the formation of large-scale structures, govern the dynamics in wide variety of fluid flows. The Rayleigh-Taylor instability (RTI) is an iconic example that leads to the development of mushroom-shaped incursions when immiscible fluids are accelerated into each other. RTI drives structure formation throughout science and engineering including table-top oil and water mixtures; supernova explosions; and inertial confinement fusion.  Despite its ubiquity, controlled laboratory RTI experiments are technically challenging.

Quantum many-body systems can host exotic phases of matter characterized by their quantum entanglement. Among them are phases with topological order. In this talk we discuss how to explore the toric code model in a field (or equivalently the Fradkin-Shenker lattice gauge theory) — a paradigmatic model hosting a Z2 topologically ordered phase and a trivial phase — on a quantum processor [1]. We then focus on the higher-form symmetries of the model. In contrast to global on-site (0-form) symmetries, higher-from symmetries act on subdimensional manifolds.

Moire superlattices in semiconductors are predicted to exhibit a rich variety of interaction-induced topological states. However, experimental demonstrations of such topological states, apart from MoTe2 superlattices [1–8], have remained scarce [9, 10]. Here, we report the first optical detection of quantum anomalous Hall (QAH) states in twisted WSe2 homobilayer (tWSe2). Specifically, we employ polarization-resolved attractive polaron spectroscopy on a dual-gated, 2degree tWSe2 and observe direct signatures of spontaneous time-reversal symmetry breaking at hole filling ν = 1.

Talk 1: Quantum Wave Atom Transforms
Marianna Podzorova - CS Grad Student

Edge states—localized electronic states at the boundaries of a material—are often attributed to structural defects or topological features in crystalline solids. In finite 𝜋-conjugated systems such as graphene nanoribbons, boron nitride, and short segments of single-walled carbon nanotubes, these edge states can lead to electron scattering and fluorescence quenching. Computational studies have shown that certain chemical modifications, such as tailored edge-passivation and fullerene-end capping, can suppress these states.

While trapped ions are well-developed technologies for both quantum computation and simulation, incorporating them into nodes of a quantum network typically requires quantum frequency conversion (QFC). QFC extends the network's operating range given that most atomic ions emit polarization-entangled photons in the visible or near-infrared wavelengths.We demonstrate two-stage, polarization-preserving QFC for shifting Ba+ single photons upwards of 375 THz to the telecom O-band for quantum networking.

Recently, an experiment using a quantum processor realized a protocol for ‘Certified Randomness’, generating remotely verifiable randomness appealing for applications involving mutually untrusting parties. This protocol builds on the success of pushing the ability of quantum computers to perform beyond-classical computational tasks and leverages the classical hardness of sampling from random quantum circuits to certify 70 kbits of entropy against a realistic adversary using best-known attacks.