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Tight Lieb–Robinson Bound for approximation ratio in quantum annealing 量子退火中近似率的李布-罗宾逊紧约束
IF 7.6 1区 物理与天体物理
npj Quantum Information Pub Date : 2024-04-17 DOI: 10.1038/s41534-024-00832-x
Arthur Braida, Simon Martiel, Ioan Todinca
{"title":"Tight Lieb–Robinson Bound for approximation ratio in quantum annealing","authors":"Arthur Braida, Simon Martiel, Ioan Todinca","doi":"10.1038/s41534-024-00832-x","DOIUrl":"https://doi.org/10.1038/s41534-024-00832-x","url":null,"abstract":"<p>Quantum annealing (QA) holds promise for optimization problems in quantum computing, especially for combinatorial optimization. This analog framework attracts attention for its potential to address complex problems. Its gate-based homologous, QAOA with proven performance, has attracted a lot of attention to the NISQ era. Several numerical benchmarks try to compare these two metaheuristics, however, classical computational power highly limits the performance insights. In this work, we introduce a parametrized version of QA enabling a precise 1-local analysis of the algorithm. We develop a tight Lieb–Robinson bound for regular graphs, achieving the best-known numerical value to analyze QA locally. Studying MaxCut over cubic graph as a benchmark optimization problem, we show that a linear-schedule QA with a 1-local analysis achieves an approximation ratio over 0.7020, outperforming any known 1-local algorithms.</p>","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"34 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140603633","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
Error-mitigated fermionic classical shadows on noisy quantum devices 噪声量子器件上的误差减弱费米经典阴影
IF 7.6 1区 物理与天体物理
npj Quantum Information Pub Date : 2024-04-16 DOI: 10.1038/s41534-024-00836-7
Bujiao Wu, Dax Enshan Koh
{"title":"Error-mitigated fermionic classical shadows on noisy quantum devices","authors":"Bujiao Wu, Dax Enshan Koh","doi":"10.1038/s41534-024-00836-7","DOIUrl":"https://doi.org/10.1038/s41534-024-00836-7","url":null,"abstract":"<p>Efficiently estimating fermionic Hamiltonian expectation values is vital for simulating various physical systems. Classical shadow (CS) algorithms offer a solution by reducing the number of quantum state copies needed, but noise in quantum devices poses challenges. We propose an error-mitigated CS algorithm assuming gate-independent, time-stationary, and Markovian (GTM) noise. For <i>n</i>-qubit systems, our algorithm, which employs the easily prepared initial state <span>(leftvert {0}^{n}rightrangle ,leftlangle {0}^{n}rightvert)</span> assumed to be noiseless, efficiently estimates <i>k</i>-RDMs with <span>(widetilde{{{{mathcal{O}}}}}(k{n}^{k}))</span> state copies and <span>(widetilde{{{{mathcal{O}}}}}(sqrt{n}))</span> calibration measurements for GTM noise with constant fidelities. We show that our algorithm is robust against noise types like depolarizing, damping, and <i>X</i>-rotation noise with constant strengths, showing scalings akin to prior CS algorithms for fermions but with better noise resilience. Numerical simulations confirm our algorithm’s efficacy in noisy settings, suggesting its viability for near-term quantum devices.</p>","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"55 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140603943","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
Entangling entanglement: coupling frequency and polarization of biphotons on demand 缠结纠缠：按需耦合双光子的频率和偏振
IF 7.6 1区 物理与天体物理
npj Quantum Information Pub Date : 2024-04-12 DOI: 10.1038/s41534-024-00837-6
Arash Riazi, Eric Y. Zhu, Dan Xu, Li Qian
{"title":"Entangling entanglement: coupling frequency and polarization of biphotons on demand","authors":"Arash Riazi, Eric Y. Zhu, Dan Xu, Li Qian","doi":"10.1038/s41534-024-00837-6","DOIUrl":"https://doi.org/10.1038/s41534-024-00837-6","url":null,"abstract":"<p>Quantum information is often carried in the frequency and polarization degrees of freedom (DoFs) in single photons and entangled photons. We demonstrate an approach to couple and decouple the frequency and polarization DoFs of broadband biphotons. Our approach is based on a nonlinear interferometer consisting of a linear dispersive medium and a polarization controller in between the two biphoton sources (nonlinear media). When the two DoFs are decoupled, maximally polarization-entangled biphotons are observed in the polarization DoF, while interference fringes are observed in the spectrum of the biphotons. When the two DoFs are coupled, by adjusting the polarization controller, interference fringes disappear from the spectrum and instead appear in the degree of polarization entanglement, varying between 0 and 1, depending on the signal and idler frequencies. Our approach offers a convenient means of tuning the polarization entanglement and can be employed for arbitrary biphoton polarization state generation.</p>","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"7 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140547433","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
Criticality-enhanced electric field gradient sensor with single trapped ions 具有单个捕获离子的临界增强型电场梯度传感器
IF 7.6 1区 物理与天体物理
npj Quantum Information Pub Date : 2024-04-10 DOI: 10.1038/s41534-024-00833-w
Theodoros Ilias, Dayou Yang, Susana F. Huelga, Martin B. Plenio
{"title":"Criticality-enhanced electric field gradient sensor with single trapped ions","authors":"Theodoros Ilias, Dayou Yang, Susana F. Huelga, Martin B. Plenio","doi":"10.1038/s41534-024-00833-w","DOIUrl":"https://doi.org/10.1038/s41534-024-00833-w","url":null,"abstract":"<p>We propose and analyze a driven-dissipative quantum sensor that is continuously monitored close to a dissipative critical point. The sensor relies on the critical open Rabi model with the spin and phonon degrees of freedom of a single trapped ion to achieve criticality-enhanced sensitivity. Effective continuous monitoring of the sensor is realized via a co-trapped ancilla ion that switches between dark and bright internal states conditioned on a ‘jump’ of the phonon population which, remarkably, achieves nearly perfect phonon counting despite a low photon collection efficiency. By exploiting both dissipative criticality and efficient continuous readout, the sensor device achieves highly precise sensing of oscillating electric field gradients at a criticality-enhanced precision scaling beyond the standard quantum limit, which we demonstrate is robust to the experimental imperfections in real-world applications.</p>","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"2 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140541488","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
Fast pseudorandom quantum state generators via inflationary quantum gates 通过膨胀量子门实现快速伪随机量子态发生器
IF 7.6 1区 物理与天体物理
npj Quantum Information Pub Date : 2024-04-10 DOI: 10.1038/s41534-024-00831-y
Claudio Chamon, Eduardo R. Mucciolo, Andrei E. Ruckenstein, Zhi-Cheng Yang
{"title":"Fast pseudorandom quantum state generators via inflationary quantum gates","authors":"Claudio Chamon, Eduardo R. Mucciolo, Andrei E. Ruckenstein, Zhi-Cheng Yang","doi":"10.1038/s41534-024-00831-y","DOIUrl":"https://doi.org/10.1038/s41534-024-00831-y","url":null,"abstract":"<p>We propose a mechanism for reaching pseudorandom quantum states, computationally indistinguishable from Haar random, with shallow log-<i>n</i> depth quantum circuits, where <i>n</i> is the number of qudits. We argue that <span>(log n)</span> depth 2-qubit-gate-based generic random quantum circuits that are claimed to provide a lower bound on the speed of information scrambling, cannot produce computationally pseudorandom quantum states. This conclusion is connected with the presence of polynomial (in <i>n</i>) tails in the stay probability of short Pauli strings that survive evolution through such shallow circuits. We show, however, that stay-probability-tails can be eliminated and pseudorandom quantum states can be accomplished with shallow <span>(log n)</span> depth circuits built from a special universal family of “inflationary” quantum (IQ) gates. We prove that IQ-gates cannot be implemented with 2-qubit gates, but can be realized either as a subset of 2-qudit-gates in <i>U</i>(<i>d</i><sup>2</sup>) with <i>d</i> ≥ 3 and <i>d</i> prime, or as special 3-qubit gates.</p>","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"47 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140547422","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
Verifying the security of a continuous variable quantum communication protocol via quantum metrology 通过量子计量学验证连续可变量子通信协议的安全性
IF 7.6 1区 物理与天体物理
npj Quantum Information Pub Date : 2024-04-04 DOI: 10.1038/s41534-024-00834-9
Lorcán O. Conlon, Biveen Shajilal, Angus Walsh, Jie Zhao, Jiri Janousek, Ping Koy Lam, Syed M. Assad
{"title":"Verifying the security of a continuous variable quantum communication protocol via quantum metrology","authors":"Lorcán O. Conlon, Biveen Shajilal, Angus Walsh, Jie Zhao, Jiri Janousek, Ping Koy Lam, Syed M. Assad","doi":"10.1038/s41534-024-00834-9","DOIUrl":"https://doi.org/10.1038/s41534-024-00834-9","url":null,"abstract":"<p>Quantum mechanics offers the possibility of unconditionally secure communication between multiple remote parties. Security proofs for such protocols typically rely on bounding the capacity of the quantum channel in use. In a similar manner, Cramér-Rao bounds in quantum metrology place limits on how much information can be extracted from a given quantum state about some unknown parameters of interest. In this work we establish a connection between these two areas. We first demonstrate a three-party sensing protocol, where the attainable precision is dependent on how many parties work together. This protocol is then mapped to a secure access protocol, where only by working together can the parties gain access to some high security asset. Finally, we map the same task to a communication protocol where we demonstrate that a higher mutual information can be achieved when the parties work collaboratively compared to any party working in isolation.</p>","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"118 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140349576","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
Black-hole powered quantum coherent amplifier 黑洞供电量子相干放大器
IF 7.6 1区 物理与天体物理
npj Quantum Information Pub Date : 2024-03-28 DOI: 10.1038/s41534-024-00817-w
Avijit Misra, Pritam Chattopadhyay, Anatoly Svidzinsky, Marlan O. Scully, Gershon Kurizki
{"title":"Black-hole powered quantum coherent amplifier","authors":"Avijit Misra, Pritam Chattopadhyay, Anatoly Svidzinsky, Marlan O. Scully, Gershon Kurizki","doi":"10.1038/s41534-024-00817-w","DOIUrl":"https://doi.org/10.1038/s41534-024-00817-w","url":null,"abstract":"<p>Atoms falling into a black hole (BH) through a cavity are shown to enable coherent amplification of light quanta powered by the BH-gravitational vacuum energy. This process can harness the BH energy towards useful purposes, such as propelling a spaceship trapped by the BH. The process can occur via transient amplification of a signal field by falling atoms that are partly excited by Hawking radiation reflected by an orbiting mirror. In the steady-state regime of thermally equilibrated atoms that weakly couple to the field, this amplifier constitutes a BH-powered quantum heat engine. The envisaged effects substantiate the thermodynamic approach to BH acceleration radiation.</p>","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"12 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140310791","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
Modeling Si/SiGe quantum dot variability induced by interface disorder reconstructed from multiperspective microscopy 通过多视角显微镜重构由界面紊乱诱发的硅/硅锗量子点变化模型
IF 7.6 1区 物理与天体物理
npj Quantum Information Pub Date : 2024-03-27 DOI: 10.1038/s41534-024-00827-8
Luis Fabián Peña, Justine C. Koepke, Joseph Houston Dycus, Andrew Mounce, Andrew D. Baczewski, N. Tobias Jacobson, Ezra Bussmann
{"title":"Modeling Si/SiGe quantum dot variability induced by interface disorder reconstructed from multiperspective microscopy","authors":"Luis Fabián Peña, Justine C. Koepke, Joseph Houston Dycus, Andrew Mounce, Andrew D. Baczewski, N. Tobias Jacobson, Ezra Bussmann","doi":"10.1038/s41534-024-00827-8","DOIUrl":"https://doi.org/10.1038/s41534-024-00827-8","url":null,"abstract":"<p>SiGe heteroepitaxial growth yields pristine host material for quantum dot qubits, but residual interface disorder can lead to qubit-to-qubit variability that might pose an obstacle to reliable SiGe-based quantum computing. By convolving data from scanning tunneling microscopy and high-angle annular dark field scanning transmission electron microscopy, we reconstruct 3D interfacial atomic structure and employ an atomistic multi-valley effective mass theory to quantify qubit spectral variability. The results indicate (1) appreciable valley splitting (VS) variability of ~50% owing to alloy disorder and (2) roughness-induced double-dot detuning bias energy variability of order 1–10 meV depending on well thickness. For measured intermixing, atomic steps have negligible influence on VS, and uncorrelated roughness causes spatially fluctuating energy biases in double-dot detunings potentially incorrectly attributed to charge disorder. Our approach yields atomic structure spanning orders of magnitude larger areas than post-growth microscopy or tomography alone, enabling more holistic predictions of disorder-induced qubit variability.</p>","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"13 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140310771","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
Low disorder and high valley splitting in silicon 硅中的低无序和高谷分裂
IF 7.6 1区 物理与天体物理
npj Quantum Information Pub Date : 2024-03-13 DOI: 10.1038/s41534-024-00826-9
Davide Degli Esposti, Lucas E. A. Stehouwer, Önder Gül, Nodar Samkharadze, Corentin Déprez, Marcel Meyer, Ilja N. Meijer, Larysa Tryputen, Saurabh Karwal, Marc Botifoll, Jordi Arbiol, Sergey V. Amitonov, Lieven M. K. Vandersypen, Amir Sammak, Menno Veldhorst, Giordano Scappucci
{"title":"Low disorder and high valley splitting in silicon","authors":"Davide Degli Esposti, Lucas E. A. Stehouwer, Önder Gül, Nodar Samkharadze, Corentin Déprez, Marcel Meyer, Ilja N. Meijer, Larysa Tryputen, Saurabh Karwal, Marc Botifoll, Jordi Arbiol, Sergey V. Amitonov, Lieven M. K. Vandersypen, Amir Sammak, Menno Veldhorst, Giordano Scappucci","doi":"10.1038/s41534-024-00826-9","DOIUrl":"https://doi.org/10.1038/s41534-024-00826-9","url":null,"abstract":"<p>The electrical characterisation of classical and quantum devices is a critical step in the development cycle of heterogeneous material stacks for semiconductor spin qubits. In the case of silicon, properties such as disorder and energy separation of conduction band valleys are commonly investigated individually upon modifications in selected parameters of the material stack. However, this reductionist approach fails to consider the interdependence between different structural and electronic properties at the danger of optimising one metric at the expense of the others. Here, we achieve a significant improvement in both disorder and valley splitting by taking a co-design approach to the material stack. We demonstrate isotopically purified, strained quantum wells with high mobility of 3.14(8) × 10<sup>5</sup> cm<sup>2</sup> V<sup>−1</sup> s<sup>−1</sup> and low percolation density of 6.9(1) × 10<sup>10</sup> cm<sup>−2</sup>. These low disorder quantum wells support quantum dots with low charge noise of 0.9(3) μeV Hz<sup>−1/2</sup> and large mean valley splitting energy of 0.24(7) meV, measured in qubit devices. By striking the delicate balance between disorder, charge noise, and valley splitting, these findings provide a benchmark for silicon as a host semiconductor for quantum dot qubits. We foresee the application of these heterostructures in larger, high-performance quantum processors.</p>","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"133 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140123910","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
Pipeline quantum processor architecture for silicon spin qubits 硅自旋量子比特的管道量子处理器架构
IF 7.6 1区 物理与天体物理
npj Quantum Information Pub Date : 2024-03-12 DOI: 10.1038/s41534-024-00823-y
S. M. Patomäki, M. F. Gonzalez-Zalba, M. A. Fogarty, Z. Cai, S. C. Benjamin, J. J. L. Morton
{"title":"Pipeline quantum processor architecture for silicon spin qubits","authors":"S. M. Patomäki, M. F. Gonzalez-Zalba, M. A. Fogarty, Z. Cai, S. C. Benjamin, J. J. L. Morton","doi":"10.1038/s41534-024-00823-y","DOIUrl":"https://doi.org/10.1038/s41534-024-00823-y","url":null,"abstract":"<p>We propose a quantum processor architecture, the qubit ‘pipeline’, in which run-time scales additively as functions of circuit depth and run repetitions. Run-time control is applied globally, reducing the complexity of control and interconnect resources. This simplification is achieved by shuttling <i>N</i>-qubit states through a large layered physical array of structures which realise quantum logic gates in stages. Thus, the circuit depth corresponds to the number of layers of structures. Subsequent <i>N</i>-qubit states are ‘pipelined’ densely through the structures to efficiently wield the physical resources for repeated runs. Pipelining thus lends itself to noisy intermediate-scale quantum (NISQ) applications, such as variational quantum eigensolvers, which require numerous repetitions of the same or similar calculations. We illustrate the architecture by describing a realisation in the naturally high-density and scalable silicon spin qubit platform, which includes a universal gate set of sufficient fidelity under realistic assumptions of qubit variability.</p>","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"8 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140124056","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
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