Quantum Brain

Papers

Live trends in quantum computing research, updated daily from arXiv.

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13,350 papers in 12 months (+7% vs prior quarter)

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Qubit Platforms

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28,250 papers found

Speed limits of two-qutrit gates

Bora Basyildiz, Zhexuan Gong, Sahel Ashhab·Oct 9, 2025

The speed of elementary quantum gates sets a limit on the speed at which quantum circuits can be applied and, as a result, the size of the computations that can be performed on a quantum computer. This limitation stems from the fact that present-day ...

Quantum Physics

Quantum Shannon Information Theory -Design of communication, cipher and sensor-

Osamu Hirota·Oct 9, 2025

One of the key aspects of Shannon's theory is that it provides guidance for designing the most efficient systems, such as minimizing errors and clarifying the limits of coding. Such theories have made great developments in the 50 years since 1948. It...

Quantum Physics

Speed of evolution in qutrit systems

Jesica Espino-González, Francisco J. Sevilla, Andrea Valdés-Hernández·Oct 9, 2025

The speed of evolution between perfectly distinguishable states is thoroughly analyzed in a closed three-level (qutrit) quantum system. Considering an evolution under an arbitrary time-independent Hamiltonian, we fully characterize the relevant param...

Quantum Physics

Optimal lower bounds for quantum state tomography

Thilo Scharnhorst, Jack Spilecki, John Wright·Oct 9, 2025

We show that $n = Ω(rd/\varepsilon^2)$ copies are necessary to learn a rank $r$ mixed state $ρ\in \mathbb{C}^{d \times d}$ up to error $\varepsilon$ in trace distance. This matches the upper bound of $n = O(rd/\varepsilon^2)$ from prior work, and the...

Quantum PhysicsComplexityData Structures

Lithographic integration of TES microcalorimeters with SQUID multiplexer circuits for large format spectrometers

Robinjeet Singh, Avirup Roy, Daniel Becker +12 more·Oct 9, 2025

Arrays of hundreds or thousands of low temperature detectors have been deployed for many experiments, both bolometers for long wavelength applications and calorimeters for shorter wavelength applications. One challenge that is common to many of these...

physics.ins-detcond-mat.supr-conphysics.app-phQuantum Physics

Interpolative separable density fitting on adaptive real space grids

Hai Zhu, Chia-Nan Yeh, Miguel A. Morales +3 more·Oct 9, 2025

We generalize the interpolative separable density fitting (ISDF) method, used for compressing the four-index electron repulsion integral (ERI) tensor, to incorporate adaptive real space grids for potentially highly localized single-particle basis fun...

physics.comp-phmath.NAQuantum Physics

Photon triplets from integrated microrings: A path towards deterministic non-Gaussianity on a chip

Samuel E. Fontaine, J. E. Sipe, Marco Liscidini +1 more·Oct 9, 2025

We propose cascaded spontaneous four-wave mixing (SFWM) in microring resonators as a scalable and efficient approach for directly generating non-Gaussian states of light. Focusing on the well-understood "low-gain" regime, we demonstrate that triplet ...

Quantum Physicsphysics.optics

AI-Driven Post-Quantum Cryptography for Cyber-Resilient V2X Communication in Transportation Cyber-Physical Systems

Akid Abrar, Sagar Dasgupta, Mizanur Rahman +1 more·Oct 9, 2025

Transportation Cyber-Physical Systems (TCPS) integrate physical elements, such as transportation infrastructure and vehicles, with cyber elements via advanced communication technologies, allowing them to interact seamlessly. This integration enhances...

Computer Science

Generating Entangled Steady States in Multistable Open Quantum Systems via Initial State Control

Diego Fallas Padilla, Raphael Kaubruegger, Adrianna Gillman +2 more·Oct 8, 2025

Entanglement underpins the power of quantum technologies, yet it is fragile and typically destroyed by dissipation. Paradoxically, the same dissipation, when carefully engineered, can drive a system toward robust entangled steady states. However, thi...

Quantum Physics

Asymptotic Gate Count Bounds for Ancilla-Free Single-Qubit Synthesis with Arithmetic Gates

Kaoru Sano, Hayata Morisaki, Seiseki Akibue·Oct 8, 2025

We study ancilla-free approximation of single-qubit unitaries $U\in {\rm SU}(2)$ by gate sequences over Clifford+$G$, where $G\in\{T,V\}$ or their generalization. Let $p$ denote the characteristic factor of the gate set (e.g., $p=2$ for $G=T$ and $p=...

Quantum PhysicsMathematical Physicsmath.NT

Conjugate queries can help

Ewin Tang, John Wright, Mark Zhandry·Oct 8, 2025

We give a natural problem over input quantum oracles $U$ which cannot be solved with exponentially many black-box queries to $U$ and $U^\dagger$, but which can be solved with constant many queries to $U$ and $U^*$, or $U$ and $U^{\mathrm{T}}$. We als...

Quantum PhysicsComplexityData Structures

Reconfigurable dissipative entanglement between many spin ensembles: from robust quantum sensing to many-body state engineering

Anjun Chu, Mikhail Mamaev, Martin Koppenhöfer +2 more·Oct 8, 2025

An attractive approach for stabilizing entangled many-body spin states is to employ engineered dissipation. Most existing proposals either target relatively simple collective spin states, or require numerous independent and complex dissipative proces...

Quantum Physicscond-mat.quant-gasAtomic Physics

Variational formulae for entropy-like functionals for states in von Neumann algebras

Andrzej Łuczak, Hanna Podsędkowska, Rafał Wieczorek·Oct 8, 2025

The paper presents variational formulae for entropy-like functionals, including Segal and Rényi entropies, for normal states on semifinite von Neumann algebras. The considered functionals are of the form $τ(f(h))$ where $τ$ is a normal faithful semif...

math.OAMathematical Physicsmath.FAmath.QA

Noisy-Syndrome Decoding of Hypergraph Product Codes

Venkata Gandikota, Elena Grigorescu, Vatsal Jha +1 more·Oct 8, 2025

Hypergraph product codes are a prototypical family of quantum codes with state-of-the-art decodability properties. Recently, Golowich and Guruswami (FOCS 2024) showed a reduction from quantum decoding to syndrome decoding for a general class of codes...

Quantum Physics

Beyond Hoeffding and Chernoff: Trading conclusiveness for advantages in quantum hypothesis testing

Kaiyuan Ji, Bartosz Regula·Oct 8, 2025

The ultimate limits of quantum state discrimination are often thought to be captured by asymptotic bounds that restrict the achievable error probabilities, notably the quantum Chernoff and Hoeffding bounds. Here we study hypothesis testing protocols ...

Quantum Physicscs.ITMathematical Physics

Nonlinear Coupling between Motional Modes in Trapped Ion Quantum Processors

Wes Johnson, Brandon Ruzic·Oct 8, 2025

Trapped-ion crystals are a leading platform for quantum information science, but achieving the high-fidelity entangling gates required for fault-tolerant quantum computing becomes harder as system size increases. As systems scale, spectral crowding m...

Quantum Physics

Mass-to-Horizon Relation and Entropy Beyond the Bekenstein-Hawking Limit

Hussain Gohar·Oct 8, 2025

We introduce a generalized mass-horizon relation applicable to cosmological horizons. This formulation provides a unified framework for deriving a broad class of Bekenstein entropy extensions motivated by statistical mechanics, quantum gravity, and p...

gr-qcQuantum Physics

Entanglement in von Neumann Algebraic Quantum Information Theory

Lauritz van Luijk·Oct 8, 2025

In quantum systems with infinitely many degrees of freedom, states can be infinitely entangled across a pair of subsystems, but are there different forms of infinite entanglement? To understand entanglement in such systems, we use a framework in whic...

Quantum PhysicsMathematical Physicsmath.OA

Correlation Lengths for Stochastic Matrix Product States

Lubashan Pathirana, Albert H. Werner·Oct 8, 2025

We introduce a general model of stochastically generated matrix product states (MPS) in which the local tensors share a common distribution and form a strictly stationary sequence, without requiring spatial independence. Under natural conditions on t...

Quantum PhysicsMathematical Physics

Constructive counterexamples to the additivity of minimum output Rényi entropy of quantum channels for all $p>1$

Harm Derksen, Benjamin Lovitz·Oct 8, 2025

We present explicit quantum channels with strictly sub-additive minimum output Rényi entropy for all $p>1$, improving upon prior constructions which handled $p>2$. Our example is provided by explicit constructions of linear subspaces with high geomet...

Quantum Physics
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