Abstract: We study Bayesian decoding of finite-energy Gottesman–Kitaev–Preskill (GKP) qubits from multi-shot homo dyne records under coherent displacement channels, in which all shots of a trial share one latent shift. Our first contribution is an α-marginalised Bayes-optimal decoder, validated shot-for shot against the exact likelihood computed from the simulator’s own wavefunction/Fock pipeline: the textbook IID […]
Abstract: We study an architecture for fault-tolerant measurement-based quantum computation (FT-MBQC) over optically-networked trapped-ion modules. The architecture is implemented with a finite number of modules and ions per module, and leverages photonic interactions for generating remote entanglement between modules and local Coulomb interactions for intra-modular entangling gates. We focus on generating the topologically protected Raussendorf–Harrington–Goyal […]
Finding the shortest vector in a lattice is a problem that is believed to be hard both for classical and quantum computers. Many major postquantum secure cryptosystems base their security on the hardness of the shortest vector problem (SVP) (Moody, 2023). Finding the best classical, quantum, or hybrid classical–quantum algorithms for the SVP is necessary […]
To perform reliable information processing in quantum computers, quantum error correction (QEC) codes are essential for the detection and correction of errors in the qubits. Among QEC codes, topological QEC codes are designed to interact between the neighboring qubits, which is a promising property for easing the implementation requirements. In addition, the locality to the […]
Large-scale quantum information processing requires the use of quantum error-correcting codes to mitigate the effects of noise in quantum devices. Topological error-correcting codes, such as surface codes, are promising candidates, as they can be implemented using only local interactions in a 2-D array of physical qubits. Procedures, such as defect braiding and lattice surgery, can […]
The quantum approximate optimization algorithm (QAOA) has been introduced as a heuristic digital quantum computing scheme to find approximate solutions of combinatorial optimization problems. We present a scheme to parallelize this approach for arbitrary all-to-all connected problem graphs in a layout of quantum bits (qubits) with nearest-neighbor interactions. The protocol consists of single qubit operations […]
In this article, we investigate the role of local information in the decoding of the repetition and surface error correction codes for the protection of quantum states. Our key result is an improvement in resource efficiency when local information is taken into account during the decoding process: the code distance associated with a given logical […]