Quantum

Paper

Beyond unital noise in variational quantum algorithms: noise-induced barren plateaus and limit sets

Phattharaporn Singkanipa and Daniel A. Lidar,

Quantum 9, 1617 (2025).

Variational quantum algorithms (VQAs) hold much promise but face the challenge of exponentially small gradients. Unmitigated, this barren plateau (BP) phenomenon leads to an exponential trai…

Paper

Measurement events relative to temporal quantum reference frames

Ladina Hausmann, Alexander Schmidhuber, and Esteban Castro-Ruiz,

Quantum 9, 1616 (2025).

The Page-Wootters formalism is a proposal for reconciling the background-dependent, quantum-mechanical notion of time with the background independence of general relativity. However, the phy…

Paper

Fundamental charges for dual-unitary circuits

Tom Holden-Dye, Lluis Masanes, and Arijeet Pal,

Quantum 9, 1615 (2025).

Dual-unitary quantum circuits have recently attracted attention as an analytically tractable model of many-body quantum dynamics. Consisting of a 1+1D lattice of 2-qudit gates arranged in a…

Paper

A thermodynamically consistent approach to the energy costs of quantum measurements

Camille L Latune and Cyril Elouard,

Quantum 9, 1614 (2025).

Considering a general microscopic model for a quantum measuring apparatus comprising a quantum probe coupled to a thermal bath, we analyze the energetic resources necessary for the realizati…

Paper

Multiplexed Quantum Communication with Surface and Hypergraph Product Codes

Shin Nishio, Nicholas Connolly, Nicolò Lo Piparo, William John Munro, Thomas Rowan Scruby, and Kae Nemoto,

Quantum 9, 1613 (2025).

Connecting multiple processors via quantum interconnect technologies could help overcome scalability issues in single-processor quantum computers. Transmission via these interconnects can be…

Paper

Designing open quantum systems with known steady states: Davies generators and beyond

Jinkang Guo, Oliver Hart, Chi-Fang Chen, Aaron J. Friedman, and Andrew Lucas,

Quantum 9, 1612 (2025).

We provide a systematic framework for constructing generic models of nonequilibrium quantum dynamics with a target stationary (mixed) state. Our framework identifies (almost) all combination…

Paper

Security of differential phase shift QKD from relativistic principles

Martin Sandfuchs, Marcus Haberland, V. Vilasini, and Ramona Wolf,

Quantum 9, 1611 (2025).

The design of quantum protocols for secure key generation poses many challenges: On the one hand, they need to be practical concerning experimental realisations. On the other hand, their the…

Paper

Relational dynamics and Page-Wootters formalism in group field theory

Andrea Calcinari and Steffen Gielen,

Quantum 9, 1610 (2025).

Group field theory posits that spacetime is emergent and is hence defined without any background notion of space or time; dynamical questions are formulated in relational terms, in particula…

Paper

Color code decoder with improved scaling for correcting circuit-level noise

Seok-Hyung Lee, Andrew Li, and Stephen D. Bartlett,

Quantum 9, 1609 (2025).

Two-dimensional color codes are a promising candidate for fault-tolerant quantum computing, as they have high encoding rates, transversal implementation of logical Clifford gates, and resour…

Paper

On the simulation of quantum multimeters

Andreas Bluhm, Leevi Leppäjärvi, and Ion Nechita,

Quantum 9, 1608 (2025).

In the quest for robust and universal quantum devices, the notion of simulation plays a crucial role, both from a theoretical and from an applied perspective. In this work, we go beyond the…

Paper

Symmetry protected topological phases under decoherence

Jong Yeon Lee, Yi-Zhuang You, and Cenke Xu,

Quantum 9, 1607 (2025).

We investigate mixed states exhibiting nontrivial topological features, focusing on symmetry-protected topological (SPT) phases under various types of decoherence. Our findings demonstrate t…

Paper

Optimizing Circuit Reusing and its Application in Randomized Benchmarking

Zhuo Chen, Guoding Liu, and Xiongfeng Ma,

Quantum 9, 1606 (2025).

Quantum learning tasks often leverage randomly sampled quantum circuits to characterize unknown systems. An efficient approach known as “circuit reusing,'' where each circuit is executed mu…

Paper

Imperfect quantum networks with tailored resource states

Maria Flors Mor-Ruiz, Julius Wallnöfer, and Wolfgang Dür,

Quantum 9, 1605 (2025).

Entanglement-based quantum networks exhibit a unique flexibility in the choice of entangled resource states that are then locally manipulated by the nodes to fulfill any request in the netwo…

Paper

Linear gate bounds against natural functions for position-verification

Vahid Asadi, Richard Cleve, Eric Culf, and Alex May,

Quantum 9, 1604 (2025).

A quantum position-verification scheme attempts to verify the spatial location of a prover. The prover is issued a challenge with quantum and classical inputs and must respond with appropria…

Paper

Streaming quantum state purification

Andrew M. Childs, Honghao Fu, Debbie Leung, Zhi Li, Maris Ozols, and Vedang Vyas,

Quantum 9, 1603 (2025).

Quantum state purification is the task of recovering a nearly pure copy of an unknown pure quantum state using multiple noisy copies of the state. This basic task has applications to quantum…

Paper

Breaking barriers in two-party quantum cryptography via stochastic semidefinite programming

Akshay Bansal and Jamie Sikora,

Quantum 9, 1602 (2025).

In the last two decades, there has been much effort in finding secure protocols for two-party cryptographic tasks. It has since been discovered that even with quantum mechanics, many such pr…

Category: Paper