1714 matching published research entries
Quantum Research · 2026-10-30
arXiv:2610.38344v1 Announce Type: new Abstract: The quantum approximate optimization algorithm (QAOA) is a paradigmatic variational quantum algorithm for combinatorial optimization problems, yet on current quantum devices the available qubit count and achievable circuit depth remain the main bottlenecks to its practical application.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38340v1 Announce Type: new Abstract: Let $M_n=(\mathrm{PU}(2)^n\rtimes S_n)\backslash\mathrm{PU}(2^n)$ be the space of projective $n$-qubit unitaries modulo local unitaries and permutations of the qubits. We prove that for all sufficiently large $n$ the manifold $M_n$ carries exactly two $\mathrm{PU}(2^n)$-invariant Einstein metrics up to scaling.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38322v1 Announce Type: new Abstract: Dynamical locality is often regarded as a limitation of shallow quantum circuits, yet we show that it can reduce the number of circuit settings required for exact evaluation of gradients with respect to shared parameters.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38299v1 Announce Type: new Abstract: In multiparameter quantum estimation, incompatible measurements can impose trade-offs among estimation errors. Understanding the precision attainable with a finite number of jointly measured copies is therefore important, but direct optimization becomes costly as the tensor product space grows exponentially.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38283v1 Announce Type: new Abstract: Heralded atom loss is a dominant noise channel in neutral atom quantum computing platforms, and losses at a two-qubit gate are strongly correlated: when one atom is lost, its gate partner is often lost too. This work shows how to exploit this correlation to construct a better decoder, focusing on [[144,12,12]] Gross code syndrome extraction circuits.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38261v1 Announce Type: new Abstract: Rapid preparation of a target quantum state and reset to the many-body ground state are essential for quantum information processing. Here, we investigate both processes in a waveguide-coupled emitter array in the low-excitation regime.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38240v1 Announce Type: new Abstract: We investigate noise propagation in encrypted quantum cloning by formulating the protocol in terms of effective recovery channels. For local single-qubit completely positive trace-preserving noise, a Pauli-basis expansion of the Kraus operators reveals a strong dependence on the location of the physical channel.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38193v1 Announce Type: new Abstract: A coherent sum of quantum circuits introduces interference that can alter the training signal. We distinguish a single linear combination of unitaries (LCU) from a circuit that repeatedly alternates branch operations and ancilla mixing.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38189v1 Announce Type: new Abstract: In fault-tolerant Clifford+T circuits, a Boolean oracle costs T gates and extra qubits, and on four or more qubits every exact Toffoli gate needs an extra qubit. Gosset, Kothari and Zhang showed that sampling a fresh random circuit for each call makes the T-count of the Toffoli gate independent of its size, but a direct implementation of their sampler uses about one…
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38183v1 Announce Type: new Abstract: Passive loss removes probability from a system and therefore seems unable to improve an unconditional target. This intuition is exact for classical population dynamics under sink-only removal: passive killing obeys a finite-strength monotonicity principle even after optimization over the remaining controls.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38148v1 Announce Type: new Abstract: Random unitaries scramble quantum information into highly nonlocal degrees of freedom, thereby providing protection from local noise. However, as demonstrated by Turkeshi and Sierant (Phys. Rev. Lett. 132, 140401, 2024 and arXiv:2603.00235), this protection may fail once local noise grows sufficiently strong.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38119v1 Announce Type: new Abstract: A coherent ensemble of polarized helium-3 nuclei and free neutrons are coupled, forming a neutron-nucleus hybrid system. The nuclei are prepared in a spin superposition, while a magnetic field induces Zeeman splitting. The resulting nuclear energy phase is coherently transferred to the neutron, producing an intensity beat at the nuclear Zeeman frequency.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38059v1 Announce Type: new Abstract: The positive-P representation for bosons allows scalable exact simulations of many-body open quantum systems, provided dissipation is strong enough to stabilise stochastic trajectories.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38049v1 Announce Type: new Abstract: Quantum open-source software provides essential infrastructure for quantum science, and artificial intelligence (AI) is reshaping its capabilities and transforming its development. However, verifying quantum software at scale remains difficult, and AI-generated contributions can increase the workload of maintainers.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38048v1 Announce Type: new Abstract: Continuous variable quantum key distribution enables two parties to extract provably secure keys for cryptography by exploiting aspects of quantum mechanics. A central challenge in achieving QKD over long distances is overcoming optical loss, which limits the secret key rates and achievable transmission distances.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.38028v1 Announce Type: new Abstract: Generative learning of a quantum measurement distribution from finite data requires choosing a model capacity that balances representation accuracy against estimation cost. We develop a bias-variance framework that decomposes the expected population Kullback-Leibler error at model capacity $s$ and sample size $N$ as $\mathcal E(s,N)=B(s)+V(s,N)$, with representation…
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.37991v1 Announce Type: new Abstract: Braiding Majorana zero modes does not by itself provide a universal set of quantum gates. Additional operations can be supplied through ancillary states, whose preparation need not have the same protection as braiding. Here, we consider purification of the non-Gaussian ancilla used for an entangling gate in Bravyi's scheme.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.37948v1 Announce Type: new Abstract: The Pusey--Barrett--Rudolph (PBR) theorem is commonly taken to establish that a pure quantum state represents a physical property of the system to which it is assigned, rather than merely encoding knowledge. In this work, I distinguish between state-first and dynamics-first physical theories, and argue that this reading presupposes the former.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.37894v1 Announce Type: new Abstract: A unified Fourier framework for quantum weight enumerators of prime-power-dimensional qudits is developed in this paper. We introduce the notions of Weyl power spectrum and Weyl-conjugation autocorrelation for the Weyl-operator quantities nderlying the Shor--Laflamme weight enumerators.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.37873v1 Announce Type: new Abstract: With D. Aerts, we showed in 2014, within the extended Bloch representation of quantum mechanics, that the Born rule can be understood as resulting from a universal average over all the possible ways in which the measurement-interactions can be selected. The cellular construction used there was since questioned, in the context of Bertrand's paradox, by N.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.37861v1 Announce Type: new Abstract: We formulate the standard quantum teleportation protocol within the framework of deformation quantization, employing the Stratonovich--Weyl (SW) correspondence and the associated star product on the coadjoint orbits of $SU(2)$. Each qubit is represented by a spherical phase space $S^2$ endowed with the Kirillov--Kostant--Souriau (KKS) symplectic structure.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.37854v1 Announce Type: new Abstract: We review a series of recent no-go theorems that extend the methodological and conceptual framework introduced by Bell's theorem to more sophisticated operational scenarios involving independent sources, quantum networks, joint measurements, and multiple observers.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.37847v1 Announce Type: new Abstract: Givens rotations with angles stored in quantum registers account for much of the cost of published quantum phase estimation algorithms based on double-factorized tensor hypercontraction and spectral amplification. These rotations create superpositions and cannot be verified directly by the basis-state evaluators used to optimize classical reversible circuits.
arXiv QuantumRead article →Quantum Research · 2026-10-30
arXiv:2610.37840v1 Announce Type: new Abstract: We provide a detailed resource estimate of the state-of-the-art sum-of-squares block encoding algorithm for electronic structure Hamiltonians of Low et al. on superconducting cat qubits.
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