Author: Anna Schmitz-Floeder

Gaussian boson sampling (GBS) is a computational scheme that can demonstrate quantum advantage under widely accepted complexity-theoretic assumptions. In GBS, squeezed bosonic states are injected into an interferometric network whose output distribution is described by classically intractable matrix functions. Notable applications of GBS include sampling molecular spectra and searching for maximum cliques in graphs. However,…

The structure of entanglement in the ground state of the harmonic chain is studied. A class of two-mode squeezed states, useful for this purpose, is identified. The entanglement of the local modes at the ends of the chain, after tracing out the centre, rapidly falls to zero as the length of the chain increases. However,…

Bosonic quantum computation encodes information in infinite-dimensional Hilbert spaces, providing a natural path to hardware-efficient error correction. One leading example is the dissipative cat qubit, which uses engineered two-photon dissipation two-photon dissipation to stabilize superpositions of well-separated coherent states. This separation exponentially suppresses bit-flip errors at the cost of polynomially increasing phase-flip rates. These highly asymmetric…

The Gottesman-Kitaev-Preskill code writes qubits into oscillators in a way that is redundant against displacements. It has been used to perform beyond break-even error correction. However, having qubits interact in a fault-tolerant manner, that is one which is “transparent” to errors, is still ongoing work. In this talk I will review the GKP code as…

Random circuit sampling (RCS) has become a central framework for demonstrating quantum computational advantage, underlying recent experiments by Google, USTC, and others. I will begin with a brief introduction to RCS and the basic complexity-theoretic ideas supporting its hardness. A key practical ingredient in these experiments is cross-entropy benchmarking (XEB), which serves as a proxy…

Quantum noise imposes a fundamental limitation on the sensitivity of interferometric gravitational-wave detectors like LIGO, manifesting as shot noise and quantum radiation pressure noise. In the paper, the authors present the first realization of frequency-dependent squeezing in full-scale gravitational-wave detectors, resulting in the reduction of both shot noise and quantum radiation pressure noise, with broadband…

A major challenge in neutral-atom quantum simulation is control. Our experimental tools are local, allowing us to “talk to” one or two atoms, but developed algorithms demand complex global operations. How can we bridge this gap? In this talk, I’ll present a systematic description for compiling any desired global, single-particle operation into a practical sequence…

Unlike their classical counterpart, quantum processes can produce fundamentally unpredictable bits. Unfortunately, the outputs of realistic quantum devices are neither uncorrelated nor uniform. Hence, we need a way of extracting perfect randomness from imperfect devices. To achieve this goal, we consider two quantum processes happening in spacelike separated locations. We then show that spacelike separation…