A Landau Level at Zero Flux, Magic, and Abelianization
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.
Building Topological Quantum Matter in Superconducting Wire Arrays
We utilize a notion of "combinatorial gauge symmetry", where the gauge symmetry involves not just local rotations of spins, but also permutations of spins. This allows the construction of exact gauge invariant Hamiltonians using just two-body interactions. Models constructed in this way include the toric code and any Abelian and Non-Abelian generalization. New models also emerge in this paradigm. An advantage of the exact symmetry: the topological energy gaps need not be limited to a perturbative regime, but could potentially persist for a wider range of parameters.
Quantum Routing and Entanglement Capacity Through Bottlenecks
To implement arbitrary quantum interactions in architectures with restricted topologies, one may simulate all-to-all connectivity by routing quantum information. Therefore, it is of natural interest to find optimal protocols and lower bounds for routing. We consider a connectivity graph, G, of 2 regions connected only through an intermediate region of a small number of qubits that form a vertex bottleneck. Existing results only imply a trivial lower bound on the entangling rate and routing time across a vertex bottleneck.
Exponentially Reduced Circuit Depths Using Trotter Error Mitigation
Abstract: Product formulae are a popular class of digital quantum simulation algorithms due to their conceptual simplicity, low overhead, and performance which often exceeds theoretical expectations. Recently, Richardson extrapolation and polynomial interpolation have been proposed to mitigate the Trotter error incurred by use of these formulae. This work provides an improved, rigorous analysis of these techniques for the task of calculating time-evolved expectation values.
Fiber Bundle Fault Tolerance of GKP Codes
Fault tolerance is a notion of fundamental importance to the field of quantum information processing. It is one of the central properties a quantum computer must possess in order to enable the achievement of large scale practical quantum computation. While a widely used, general, and intuitive concept, within the literature the term fault tolerant is often applied to specific procedures in an ad-hoc fashion tailored to details of the context or platform under discussion.
The Quantum Reform of the Modern Metric System: Mass becomes quantum, and electrical measurements become honest
JQI Fellow William D. Phillips will deliver the 2024 Paint Branch Distinguished Lecture in Applied Physics, a lectureship sponsored by the Institute for Research in Electronics & Applied Physics.
Automated Distribution of Entanglement in New York City / Discussion of Startup Life
In the first half of this talk, I'll discuss Qunnect's approach to quantum networking based on warm-atomic ensembles. I'll introduce some of the devices that we build to distribute entanglement over long distances, and experiments we've performed on our GothamQ testbed in New York City. In the second half I'll talk about what it's like to work at a startup, and welcome audience questions on the topic.
Long-range entangled quantum matter from measurement and feedback
Long-range entangled states of matter encompass a variety of exotic quantum phenomena, ranging from topological orders to quantum criticality. In this talk, I will discuss recent advances in leveraging mid-circuit measurements and unitary feedback to efficiently generate these entangled many-body states.
Quantum Application, Parallel Operation and Noise Characterization in a Trapped-Ion Quantum Computer
Dissertation Committee Chair: Steven Rolston
Committee: Norbert M. Linke, Avik Dutt, Yu Liu, Christopher Jarzynski
An automata-based approach for quantum circuit/program verification
We present a new method for analyzing and identifying errors in quantum circuits. In our approach, we define the problem using a triple {P}C{Q}, where the task is to determine whether a given set P of quantum states at the input of a circuit C produces a set of quantum states at the output that is equal to, or included in, a set Q. We propose a technique that utilizes tree automata to represent sets of quantum states efficiently, and we develop algorithms to apply the operations of quantum gates within this representation.