Quantum

Paper

Out of the Loop: Structural Approximation of Optimisation Landscapes and non-Iterative Quantum Optimisation

Tom Krüger and Wolfgang Mauerer,

Quantum 9, 1903 (2025).

The Quantum Approximate Optimisation Algorithm (QAOA) is a widely studied quantum-classical iterative heuristic for combinatorial optimisation. While QAOA targets problems in complexity clas…

Paper

Cost of Simulating Entanglement in Steering Scenarios

Yujie Zhang, Jiaxuan Zhang, and Eric Chitambar,

Quantum 9, 1902 (2025).

Quantum entanglement is a fundamental feature of quantum mechanics, yet certain entangled states that are unsteerable can be classically simulated in steering scenarios, making them unable t…

Paper

Comparing quantum and classical Monte Carlo algorithms for estimating Betti numbers of clique complexes

Ismail Yunus Akhalwaya, Ahmed Bhayat, Adam Connolly, Steven Herbert, Lior Horesh, Julien Sorci, and Shashanka Ubaru,

Quantum 9, 1901 (2025).

Several quantum and classical Monte Carlo algorithms for Betti Number Estimation (BNE) on clique complexes have recently been proposed, though it is unclear how their performances compare. W…

Paper

Complexity of Fermionic 2-SAT

Maarten Stroeks and Barbara M. Terhal,

Quantum 9, 1900 (2025).

We introduce the fermionic satisfiability problem, Fermionic $k$-SAT: this is the problem of deciding whether there is a fermionic state in the null-space of a collection of fermionic, parity-…

Paper

Fiber Bundle Fault Tolerance of GKP Codes

Ansgar G. Burchards, Steven T. Flammia, and Jonathan Conrad,

Quantum 9, 1899 (2025).

We investigate multi-mode GKP (Gottesman–Kitaev–Preskill) quantum error-correcting codes from a geometric perspective. First, we construct their moduli space as a quotient of groups and exhi…

Paper

Learning-Driven Annealing with Adaptive Hamiltonian Modification for Solving Large-Scale Problems on Quantum Devices

Sebastian Schulz, Dennis Willsch, and Kristel Michielsen,

Quantum 9, 1898 (2025).

We present Learning-Driven Annealing (LDA), a framework that links individual quantum annealing evolutions into a global solution strategy to mitigate hardware constraints such as short anne…

Paper

Effective Distance of Higher Dimensional HGPs and Weight-Reduced Quantum LDPC Codes

Shi Jie Samuel Tan and Lev Stambler,

Quantum 9, 1897 (2025).

Quantum error correction plays a prominent role in the realization of quantum computation, and quantum low-density parity-check (qLDPC) codes are believed to be practically useful stabilizer…

Paper

Error Bounds for Open Quantum Systems with Harmonic Bosonic Bath

Kaizhao Liu and Jianfeng Lu,

Quantum 9, 1896 (2025).

We investigate the dependence of physical observable of open quantum systems with Bosonic bath on the bath correlation function. We provide an error estimate of the difference of physical ob…

Paper

Efficient Classical Simulation of the DQC1 Circuit with Zero Discord

Shalin Jose, Akshay Kannan Sairam, and Anil Shaji,

Quantum 9, 1895 (2025).

A path for efficient classical simulation of the DQC1 circuit that estimates the trace of an implementable unitary under the zero discord condition [17] is presented. This result reinforces…

Paper

Quantum bounds for compiled XOR games and $d$-outcome CHSH games

Matilde Baroni, Quoc-Huy Vu, Boris Bourdoncle, Eleni Diamanti, Damian Markham, and Ivan Šupić,

Quantum 9, 1894 (2025).

Nonlocal games play a crucial role in quantum information theory and have numerous applications in certification and cryptographic protocols. Kalai et al. (STOC 2023) introduced a procedure…

Paper

Effectiveness of the syndrome extraction circuit with flag qubits on IBM quantum hardware

Younghun Kim, Hansol Kim, Jeongsoo Kang, Wonjae Choi, and Younghun Kwon,

Quantum 9, 1893 (2025).

Large-scale quantum circuits are required to exploit the advantages of quantum computers. Despite significant advancements in quantum hardware, scalability remains a challenge, with errors a…

Paper

Missing Puzzle Pieces in the Performance Landscape of the Quantum Approximate Optimization Algorithm

Elisabeth Wybo and Martin Leib,

Quantum 9, 1892 (2025).

We consider the maximum cut and maximum independent set problems on random regular graphs in the infinite-size limit, and calculate the energy densities achieved by QAOA for high degrees up…

Paper

Indefinite causal order strategy does not improve the estimation of group action

Masahito Hayashi,

Quantum 9, 1891 (2025).

We consider estimation of unknown unitary operation when the set of possible unitary operations is given by a projective unitary representation of a compact group. We show that neither indef…

Paper

A Mathematical Structure for Amplitude-Mixing Error-Transparent Gates for Binomial Codes

Owen C. Wetherbee, Saswata Roy, Baptiste Royer, and Valla Fatemi,

Quantum 9, 1890 (2025).

Bosonic encodings of quantum information offer hardware-efficient, noise-biased approaches to quantum error correction relative to qubit register encodings. Implementations have focused in p…

Paper

Quantum circuit synthesis with SQiSW

Jialiang Tang, Jialin Zhang, and Xiaoming Sun,

Quantum 9, 1889 (2025).

The primary objective of quantum circuit synthesis is to efficiently and accurately realize specific quantum algorithms or operations utilizing a predefined set of quantum gates, while also…

Paper

Observable-projected ensembles

Alexey Milekhin and Sara Murciano,

Quantum 9, 1888 (2025).

Measurements in many-body quantum systems can generate non-trivial phenomena, such as preparation of long-range entangled states, dynamical phase transitions, or measurement-altered critical…

Category: Paper