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
Abstract: 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.
Optimization by Decoded Quantum Interferometry
Abstract: In this talk I will describe Decoded Quantum Interferometry (DQI), a quantum algorithm for reducing classical optimization problems to classical decoding problems by exploiting structure in the Fourier spectrum of the objective function. (See: https://arxiv.org/abs/2408.08292.) For a regression problem called optimal polynomial intersection, which has been previously studied in the contexts of coding theory and cryptanalysis, we believe DQI achieves an exponential quantum speedup.
The Weak Generalized Bunching Conjecture
Abstract: There has been interest in the dynamics of noninteracting bosons because of the boson sampling problem. These dynamics can be difficult to predict because of the complicated interference patterns that arise due to their indistinguishability. However, if there are unobserved, hidden degrees of freedom, the indistinguishability can be disrupted in the observations. The generalized bunching probability is defined to be the probability that noninteracting bosons undergo linear optical evolution and all arrive in a subset of sites.
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.
An automata-based approach for quantum circuit/program verification
Abstract: 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.
Fiber Bundle Fault Tolerance of GKP Codes
Abstract: 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.
New Design Packs Two Qubits into One Superconducting Junction
Quantum computers are potentially revolutionary devices and the basis of a growing industry. However, their technology isn’t standardized yet, and researchers are still studying the physics behind the diverse ways to build these quantum devices. Even the most basic building blocks of a quantum computer—qubits—are still an active research topic.