Quantum

Paper

Macroscopic quantum coherence and entanglement in mechanical systems

Benjamin Yadin and Matteo Fadel,

Quantum 10, 2257 (2026).

The notion of a macroscopic quantum state must be pinned down in order to assess how well experiments probe the large-scale limits of quantum mechanics. However, the issue of quantifying so-…

Paper

Re-uploading quantum data: a universal function approximator for quantum inputs

Hyunho Cha, Daniel K. Park, and Jungwoo Lee,

Quantum 10, 2256 (2026).

Quantum data re-uploading has proved powerful for classical inputs, where repeatedly encoding features into a small circuit yields universal function approximation. Extending this idea to qu…

Paper

Quantum Authenticated Key Expansion with Key Recycling

Wen Yu Kon, Jefferson Chu, Kevin Han Yong Loh, Obada Alia, Omar Amer, Marco Pistoia, Kaushik Chakraborty, and Charles Lim,

Quantum 10, 2255 (2026).

Data privacy and authentication are two main security requirements for remote access and cloud services. While QKD has been explored to address data privacy concerns, oftentimes its use is s…

Paper

Certified bounds on optimization problems in quantum theory

Younes Naceur, Jie Wang, Victor Magron, and Antonio Acín,

Quantum 10, 2254 (2026).

Semidefinite relaxations of polynomial optimization have become a central tool for addressing the non-convex optimization problems over non-commutative operators that are ubiquitous in quant…

Paper

A Counterexample to the Optimality Conjecture in Convex Quantum Channel Optimization

Jianting Yang,

Quantum 10, 2253 (2026).

This paper presents a counterexample to the optimality conjecture for the trace distance based optimal state transformation problem proposed by Coutts et al. [Quantum 5, 448 (2021)]. The con…

Paper

Towards quantum computing Feynman diagrams in hybrid qubit-oscillator devices

S. Varona, S. Saner, O. BÄzÄvan, G. Araneda, G. Aarts, and A. Bermudez,

Quantum 10, 2252 (2026).

We show that recent experiments in hybrid qubit-oscillator devices that measure the phase-space characteristic function of the oscillator via the qubit can be seen through the lens of functi…

Paper

Optimal phase estimation in the presence of correlated dephasing

Srijon Ghosh, Arkadiusz Kobus, Stanisław Kurdziałek, and Rafał Demkowicz-Dobrzański,

Quantum 10, 2251 (2026).

We investigate optimal metrological protocols for phase estimation in the presence of correlated dephasing noise, including spin-squeezed state sensing strategies as well as parallel and ada…

Paper

Noncontextuality inequalities for prepare-transform-measure scenarios

David Schmid, Roberto D. Baldijão, John H. Selby, Ana Belén Sainz, and Robert W. Spekkens,

Quantum 10, 2250 (2026).

We provide the first systematic technique for deriving witnesses of contextuality in prepare-transform-measure scenarios. More specifically, we show how linear quantifier elimination can be…

Paper

A General Framework for Gradient-Based Optimization of Superconducting Quantum Circuits using Qubit Discovery as a Case Study

Taha Rajabzadeh, Alex Boulton-McKeehan, Sam Bonkowsky, David I. Schuster, and Amir H. Safavi-Naeini,

Quantum 10, 2249 (2026).

Engineering the Hamiltonian of a quantum system is fundamental to the design of quantum systems. Automating Hamiltonian design through gradient-based optimization can dramatically accelerate…

Paper

Proof of hiding conjecture in Gaussian boson sampling

Laura Shou, Sarah H. Miller, and Victor Galitski,

Quantum 10, 2248 (2026).

Gaussian boson sampling (GBS) is a promising protocol for demonstrating quantum computational advantage. One of the key steps in the argument for classical hardness of GBS is the so-called “…

Paper

Floquet-ADAPT-VQE: A Quantum Algorithm to Simulate Non-Equilibrium Physics in Periodically Driven Systems

Abhishek Kumar, Karunya Shirali, Nicholas J. Mayhall, Sophia E. Economou, and Edwin Barnes,

Quantum 10, 2247 (2026).

Periodically driven quantum systems exhibit many fascinating phenomena absent in equilibrium systems, but their simulation is more challenging than that of static systems. Consequently, quan…

Paper

Variational Perturbation Theory in Open Quantum Systems for Efficient Steady State Computation

André Melo, Gaspard Beugnot, and Fabrizio Minganti,

Quantum 10, 2246 (2026).

Determining the steady state of an open quantum system is crucial for characterizing quantum devices and studying various physical phenomena. Often, computing a single steady state is insuff…

Paper

A Symmetry-Enabled Direct Quantum Protocol for Many-Body Green’s Functions

Changhao Yi and Cunlu Zhou,

Quantum 10, 2245 (2026).

We present a symmetry-enabled direct quantum protocol for computing many-body Green's functions, a central tool for studying strongly correlated quantum systems. Our protocol relies only on…

Paper

Failure of the mean-field Hartree approximation for a bosonic many-body system with non-Hermitian Hamiltonian

Matias Ginzburg, Simone Rademacher, and Giacomo De Palma,

Quantum 10, 2244 (2026).

Mean-field Hartree theory is a central tool for reducing many-body dynamics to an effective one-particle evolution. This approximation has been employed when the Hamiltonian governing the ma…

Paper

Symmetry defects and gauging for quantum states with matrix product unitary symmetries

Adrián Franco-Rubio, Arkadiusz Bochniak, and J. Ignacio Cirac,

Quantum 10, 2243 (2026).

In this work, we examine the consequences of the existence of a finite group of matrix product unitary (MPU) symmetries for matrix product states (MPS). We generalize the well-understood pic…

Paper

The three kinds of three-qubit entanglement

Szilárd Szalay,

Quantum 10, 2242 (2026).

We construct an important missing piece in the entanglement theory of pure three-qubit states, which is a polynomial measure of W-entanglement. This works in parallel to the three-tangle, wh…

Category: Paper