npj Quantum Information最新文献

Steering nonlocality in high-speed telecommunication system without detection loophole

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-24 DOI: 10.1038/s41534-025-01021-0

Qiang Zeng, Huihong Yuan, Haoyang Wang, Lai Zhou, Zhiliang Yuan

{"title":"Steering nonlocality in high-speed telecommunication system without detection loophole","authors":"Qiang Zeng, Huihong Yuan, Haoyang Wang, Lai Zhou, Zhiliang Yuan","doi":"10.1038/s41534-025-01021-0","DOIUrl":"https://doi.org/10.1038/s41534-025-01021-0","url":null,"abstract":"Nonlocal correlation represents the key feature of quantum mechanics, and is an exploitable resource in quantum information processing. However, the loophole issues and the associated applicability compromises hamper the practical applications. We report the first time-bin entangled detection-loophole-free steering nonlocality demonstration in a fully chip-fiber telecommunication system, with an ultra-fast measurement switching rate (1.25 GHz). In this endeavor, we propose the phase-encoding measurement scheme to adapt the system to time-bin degree of freedom, and design and fabricate a low-loss silicon chip for efficient entanglement generation. An asymmetric configuration is introduced to mimic the active measurement implementation at the steering party thus bypassing the phase modulation loss. Consequently, we build a fiber-optic setup that can overcome the detection efficiency required by conclusive quantum steering with multiple actively switched measurement settings. Our setup presents an immediate platform for exploring applications based on steering nonlocality, especially for quantum communication.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"259 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143872892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Long optical and electron spin coherence times for erbium ions in silicon

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-18 DOI: 10.1038/s41534-025-01008-x

Ian R. Berkman, Alexey Lyasota, Gabriele G. de Boo, John G. Bartholomew, Shao Qi Lim, Brett C. Johnson, Jeffrey C. McCallum, Bin-Bin Xu, Shouyi Xie, Nikolay V. Abrosimov, Hans-Joachim Pohl, Rose L. Ahlefeldt, Matthew J. Sellars, Chunming Yin, Sven Rogge

{"title":"Long optical and electron spin coherence times for erbium ions in silicon","authors":"Ian R. Berkman, Alexey Lyasota, Gabriele G. de Boo, John G. Bartholomew, Shao Qi Lim, Brett C. Johnson, Jeffrey C. McCallum, Bin-Bin Xu, Shouyi Xie, Nikolay V. Abrosimov, Hans-Joachim Pohl, Rose L. Ahlefeldt, Matthew J. Sellars, Chunming Yin, Sven Rogge","doi":"10.1038/s41534-025-01008-x","DOIUrl":"https://doi.org/10.1038/s41534-025-01008-x","url":null,"abstract":"Spins in silicon that are accessible via a telecom-compatible optical transition are a versatile platform for quantum information processing that can leverage the well-established silicon nanofabrication industry. Key to these applications are long coherence times on the optical and spin transitions to provide a robust system for interfacing photonic and spin qubits. Here, we report telecom-compatible Er3+ sites with long optical and electron spin coherence times, measured within a nuclear spin-free silicon crystal (<0.01 % 29Si) using optical detection. We investigate two sites and find 0.1 GHz optical inhomogeneous linewidths and homogeneous linewidths below 70 kHz for both sites. We measure the electron spin coherence time of both sites using optically detected magnetic resonance and observe Hahn echo decay constants of 0.8 ms and 1.2 ms at ~ 11 mT. These optical and spin properties of Er3+:Si are an important milestone towards using optically accessible spins in silicon for a broad range of quantum information processing applications.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"49 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143849610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Unified framework for matchgate classical shadows

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-16 DOI: 10.1038/s41534-025-01015-y

Valentin Heyraud, Héloise Chomet, Jules Tilly

{"title":"Unified framework for matchgate classical shadows","authors":"Valentin Heyraud, Héloise Chomet, Jules Tilly","doi":"10.1038/s41534-025-01015-y","DOIUrl":"https://doi.org/10.1038/s41534-025-01015-y","url":null,"abstract":"Estimating quantum fermionic properties is a computationally difficult yet crucial task for the study of electronic systems. Recent developments have begun to address this challenge by introducing classical shadows protocols relying on sampling of Fermionic Gaussian Unitaries (FGUs): a class of transformations in fermionic space which can be conveniently mapped to matchgates circuits. The different protocols proposed in the literature use different sub-ensembles of the orthogonal group O(2n) to which FGUs can be associated. We propose an approach that unifies these different protocols, proving their equivalence, and deriving from it an optimal sampling scheme. We begin by demonstrating that the first three moments of the FGU ensemble associated with SO(2n) and of its intersection with the Clifford group are equal, generalizing a result known for O(2n) and addressing a question raised in previous works. Building on this proof, we establish the equivalence between the shadows protocols resulting from FGU ensembles analyzed in the literature. Finally, from our results, we propose a sampling scheme for a small sub-ensemble of matchgates circuits that is optimal in terms of number of gates and that inherits the performances guarantees of the previous ensembles.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"26 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143836729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Universal term of entanglement entropy in the π-flux Hubbard model

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-15 DOI: 10.1038/s41534-025-01010-3

Yuan Da Liao

引用次数: 0

Dephasing and error dynamics affecting a singlet-triplet qubit during coherent spin shuttling

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-12 DOI: 10.1038/s41534-025-00996-0

Natalie D. Foster, Jacob D. Henshaw, Martin Rudolph, Dwight R. Luhman, Ryan M. Jock

{"title":"Dephasing and error dynamics affecting a singlet-triplet qubit during coherent spin shuttling","authors":"Natalie D. Foster, Jacob D. Henshaw, Martin Rudolph, Dwight R. Luhman, Ryan M. Jock","doi":"10.1038/s41534-025-00996-0","DOIUrl":"https://doi.org/10.1038/s41534-025-00996-0","url":null,"abstract":"Quantum information transport over micron to millimeter scale distances is critical for the operation of practical quantum processors based on spin qubits. One method of achieving a long-range interaction is by coherent electron spin shuttling through an array of silicon quantum dots. In order to execute many shuttling operations with high fidelity, it is essential to understand the dynamics of qubit dephasing and relaxation during the shuttling process in order to mitigate them. However, errors arising after many repeated shuttles are not yet well documented. Here, we probe decay dynamics contributing to dephasing and relaxation of a singlet-triplet qubit during coherent spin shuttling over many N repeated shuttle operations, in a small external magnetic field B0 ≈ 0−10 mT, and in the absence of a micromagnet. We find that losses are dominated by magnetic dephasing, most visible for small N < 103. However, incoherent spin-flip type shuttle errors become evident for large N > 103. Additionally, we estimate shuttle error rates below 10−4 out to at least N = 103, representing an encouraging figure for future implementations of spin shuttling to entangle distant qubits.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"50 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A simple and efficient joint measurement strategy for estimating fermionic observables and Hamiltonians

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-07 DOI: 10.1038/s41534-025-00957-7

Joanna Majsak, Daniel McNulty, Michał Oszmaniec

{"title":"A simple and efficient joint measurement strategy for estimating fermionic observables and Hamiltonians","authors":"Joanna Majsak, Daniel McNulty, Michał Oszmaniec","doi":"10.1038/s41534-025-00957-7","DOIUrl":"https://doi.org/10.1038/s41534-025-00957-7","url":null,"abstract":"We propose a simple scheme to estimate fermionic observables and Hamiltonians relevant in quantum chemistry and correlated fermionic systems. Our approach is based on implementing a measurement that jointly measures noisy versions of any product of two or four Majorana operators in an N mode fermionic system. To realize our measurement we use: (i) a randomization over a set of unitaries that realize products of Majorana fermion operators; (ii) a unitary, sampled at random from a constant-size set of suitably chosen fermionic Gaussian unitaries; (iii) a measurement of fermionic occupation numbers; (iv) suitable post-processing. Our scheme can estimate expectation values of all quadratic and quartic Majorana monomials to ϵ precision using ({mathcal{O}}(Nlog (N)/{epsilon }^{2})) and ({mathcal{O}}({N}^{2}log (N)/{epsilon }^{2})) measurement rounds respectively, matching the performance offered by fermionic classical shadows1,2. In certain settings, such as a rectangular lattice of qubits which encode an N mode fermionic system via the Jordan-Wigner transformation, our scheme can be implemented in circuit depth ({mathcal{O}}({N}^{1/2})) with ({mathcal{O}}({N}^{3/2})) two-qubit gates, offering an improvement over fermionic and matchgate classical shadows that require depth ({mathcal{O}}(N)) and ({mathcal{O}}({N}^{2})) two-qubit gates. By benchmarking our method on exemplary molecular Hamiltonians and observing performances comparable to fermionic classical shadows, we demonstrate a novel, competitive alternative to existing strategies.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"31 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143789694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Landau–Zener without a qubit: multiphoton sidebands interaction and signatures of dissipative quantum chaos

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-07 DOI: 10.1038/s41534-025-00984-4

Léo Peyruchat, Fabrizio Minganti, Marco Scigliuzzo, Filippo Ferrari, Vincent Jouanny, Franco Nori, Vincenzo Savona, Pasquale Scarlino

{"title":"Landau–Zener without a qubit: multiphoton sidebands interaction and signatures of dissipative quantum chaos","authors":"Léo Peyruchat, Fabrizio Minganti, Marco Scigliuzzo, Filippo Ferrari, Vincent Jouanny, Franco Nori, Vincenzo Savona, Pasquale Scarlino","doi":"10.1038/s41534-025-00984-4","DOIUrl":"https://doi.org/10.1038/s41534-025-00984-4","url":null,"abstract":"Landau–Zener–Stückelberg–Majorana (LZSM) interference occurs when qubit parameters are periodically modulated across avoided level crossings. We explore this phenomenon in nonlinear multilevel bosonic systems, where interference is influenced by multiple energy levels. We fabricate two superconducting resonators with flux-tunable Josephson junction arrays. The first device, exhibiting weak nonlinearity, behaves like a linear resonator under weak driving but shows LZSM interference akin to two-level systems. With stronger driving, nonlinear effects alter the interference pattern. We theoretically demonstrate that merging LZSM peaks can lead to dissipative quantum chaos. In the second device, where nonlinearity exceeds photon-loss rates, we observe additional LZSM peaks from Kerr multiphoton resonances. Under Floquet theory, these resonances represent synthetic modes of coupled nonlinear cavities, revealing effective coupling as modulation parameters vary. Our findings advance the understanding of LZSM physics and emphasize the control of nonlinear Floquet states and the emergence of chaos in engineered systems, with significant implications for novel applications in quantum dynamics and quantum control.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"17 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143789692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Frequency-bin entanglement-based Quantum Key Distribution

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-06 DOI: 10.1038/s41534-025-00991-5

Noemi Tagliavacche, Massimo Borghi, Giulia Guarda, Domenico Ribezzo, Marco Liscidini, Davide Bacco, Matteo Galli, Daniele Bajoni

{"title":"Frequency-bin entanglement-based Quantum Key Distribution","authors":"Noemi Tagliavacche, Massimo Borghi, Giulia Guarda, Domenico Ribezzo, Marco Liscidini, Davide Bacco, Matteo Galli, Daniele Bajoni","doi":"10.1038/s41534-025-00991-5","DOIUrl":"https://doi.org/10.1038/s41534-025-00991-5","url":null,"abstract":"Entanglement is an essential ingredient in many quantum communication protocols. In particular, entanglement can be exploited in quantum key distribution (QKD) to generate two correlated random bit strings whose randomness is guaranteed by the nonlocal property of quantum mechanics. Most of QKD protocols tested to date rely on polarization and/or time-bin encoding. Despite compatibility with existing fiber-optic infrastructure and ease of manipulation with standard components, frequency-bin QKD have not yet been fully explored. Here we report a demonstration of entanglement-based QKD using frequency-bin encoding. We implement the BBM92 protocol using photon pairs generated by two independent, high-finesse, ring resonators on a silicon photonic chip. We perform a passive basis selection scheme and simultaneously record sixteen projective measurements. A key finding is that frequency-bin encoding is sensitive to the random phase noise induced by thermal fluctuations of the environment. To correct for this effect, we developed a real-time adaptive phase rotation of the measurement basis, achieving stable transmission over a 26 km fiber spool with a secure key rate ≥ 4.5 bit/s. Our work introduces a new degree of freedom for the realization of entangled based QKD protocols in telecom networks.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"73 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143784810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Quantum sensing with duplex qubits of silicon vacancy centers in SiC at room temperature

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-05 DOI: 10.1038/s41534-025-01011-2

Kosuke Tahara, Shin-ichi Tamura, Haruko Toyama, Jotaro J. Nakane, Katsuhiro Kutsuki, Yuichi Yamazaki, Takeshi Ohshima

{"title":"Quantum sensing with duplex qubits of silicon vacancy centers in SiC at room temperature","authors":"Kosuke Tahara, Shin-ichi Tamura, Haruko Toyama, Jotaro J. Nakane, Katsuhiro Kutsuki, Yuichi Yamazaki, Takeshi Ohshima","doi":"10.1038/s41534-025-01011-2","DOIUrl":"https://doi.org/10.1038/s41534-025-01011-2","url":null,"abstract":"The silicon vacancy center in Silicon Carbide (SiC) provides an optically addressable qubit at room temperature in its spin-(frac{3}{2}) electronic state. However, optical spin initialization and readout are less efficient compared to those of spin-1 systems, such as nitrogen-vacancy centers in diamond, under non-resonant optical excitation. Spin-dependent fluorescence exhibits contrast only between (| m=pm 3/2left.rightrangle) and (| m=pm 1/2left.rightrangle) states, and optical pumping does not create a population difference between (| +1/2left.rightrangle) and (| -1/2left.rightrangle) states. Thus, operating one qubit (e.g., (left{| +3/2left.rightrangle ,| +1/2left.rightrangle right}) states) leaves the population in the remaining state ((| -1/2left.rightrangle)) unaffected, contributing to background in optical readout. To mitigate this problem, we propose a sensing scheme based on duplex qubit operation in the quartet, using microwave pulses with two resonant frequencies to simultaneously operate (left{| +3/2left.rightrangle ,| +1/2left.rightrangle right}) and (left{| -1/2left.rightrangle ,| -3/2left.rightrangle right}). Experimental results demonstrate that this approach doubles signal contrast in optical readout and improves sensitivity in AC magnetometry compared to simplex operation.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"16 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143782626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Industrial 300 mm wafer processed spin qubits in natural silicon/silicon-germanium

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-05 DOI: 10.1038/s41534-025-01016-x

Thomas Koch, Clement Godfrin, Viktor Adam, Julian Ferrero, Daniel Schroller, Noah Glaeser, Stefan Kubicek, Ruoyu Li, Roger Loo, Shana Massar, George Simion, Danny Wan, Kristiaan De Greve, Wolfgang Wernsdorfer

{"title":"Industrial 300 mm wafer processed spin qubits in natural silicon/silicon-germanium","authors":"Thomas Koch, Clement Godfrin, Viktor Adam, Julian Ferrero, Daniel Schroller, Noah Glaeser, Stefan Kubicek, Ruoyu Li, Roger Loo, Shana Massar, George Simion, Danny Wan, Kristiaan De Greve, Wolfgang Wernsdorfer","doi":"10.1038/s41534-025-01016-x","DOIUrl":"https://doi.org/10.1038/s41534-025-01016-x","url":null,"abstract":"The realisation of a universal quantum computer will require the operation of many thousands to millions of coherently coupled qubits. The possibility of using existing industrial semiconductor fabrication techniques and infrastructure for up-scaling and reproducibility makes silicon based spin qubits one of the most promising platforms to achieve this goal. The implementation of the up to now largest semiconductor based quantum processor was realised in a silicon/silicon-germanium heterostructure known for its low charge noise, long qubit coherence times and fast driving speeds, but the high structural complexity creates challenges for industrial implementations. Here we demonstrate quantum dots hosted in a natural Si/SiGe heterostructure fully fabricated by an industrial 300 mm semiconductor wafer process line from heterostructure growth to Co micromagnet monolithic integration. We report charge noise values below 2 μeV/(sqrt{{rm{Hz}}}), spin relaxation times exceeding 1 s, and coherence times ({T}_{2}^{* }) and ({T}_{2}^{H}) of 1 μs and 50 μs respectively, for quantum wells grown using natural silicon. Further, we achieve Rabi frequencies up to 5 MHz and single qubit gate fidelities above 99%. In addition to scalability, the high reproducibility of the 300 mm processes enables the deterministic study of qubit metric dependencies on process parameters, which is essential for optimising qubit quality.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"70 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143782629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0