The question of how quantities, like entanglement and coherence, depend on the number of copies of a given state $ρ$ is addressed. This is a hard problem, often involving optimizations over Hilbert spaces of large dimensions. Here, we propose a way to circumvent the direct evaluation of such quantities, provided that the employed measures satisfy a self-similarity property. We say that a quantity ${\cal E}(ρ^{\otimes N})$ is {\it scalable} if it can be described as a function of the variables $\{{\cal E}(ρ^{\otimes i_1}),\dots,{\cal E}(ρ^{\otimes i_q}); N\}$ for $N>i_j$, while, preserving the tensor-product structure. If analyticity is assumed, recursive relations can be derived for the Maclaurin series of ${\cal E}(ρ^{\otimes N})$, which enable us to determine its possible functional forms (in terms of the mentioned variables). In particular, we find that if ${\cal E}(ρ^{\otimes 2^n})$ depends only on ${\cal E}(ρ)$, ${\cal E}(ρ^{\otimes 2})$, and $n$, then it is completely determined by Fibonacci polynomials, to leading order. We show that the one-shot distillable (OSD) entanglement is well described as a scalable measure for several families of states. For a particular two-qutrit state $\varrho$, we determine the OSD entanglement for $\varrho^{\otimes 96}$ from smaller tensorings, with an accuracy of $97 \%$ and no extra computational effort. Finally, we show that superactivation of non-additivity may occur in this context.
Non-stabilizerness or magic resource characterizes the amount of non-Clifford operations needed to prepare quantum states. It is a crucial resource for quantum computing and a necessary condition for quantum advantage. However, quantifying magic resource beyond a few qubits has been a major challenge. Here, we introduce efficient measures of magic resource for pure quantum states with a sampling cost that is independent of the number of qubits. Our method uses Bell measurements over two copies of a state, which we implement in experiment together with a cost-free error mitigation scheme. We sh…
Time-reversal Interferometry Using Cat States with Scalable Entangling Resources
DEVCOM Army Research Laboratory(美国国防部陆军研究实验室);MIT-Harvard Center for Ultracold Atoms and Research Laboratory of Electronics, Massachusetts Institute of Technology(麻省理工学院哈佛超冷原子中心及电子研究实验室);Department of Applied Physics, Stanford University(斯坦福大学应用物理系);Department of Physics, University of Connecticut(康涅狄格大学物理系);Institute of Quantum Physics and Center for Integrated Quantum Science and Technology (IQST), Ulm University(乌尔姆大学量子物理研究所及集成量子科学与技术中心)
While the Rydberg-blockade regime provides the natural setting for creating $W$-type entanglement with cold neutral atoms, it is demonstrated here that a scalable entanglement resource of this type can even be obtained under completely different physical circumstances. To be more precise, a special instance of twisted $W$ states -- namely, $π$-twisted ones -- can be engineered in one-dimensional arrays of cold neutral atoms with Rydberg-dressed resonant dipole-dipole interaction. In particular, it is shown here that this is possible even when a (dressed) Rydberg excitation is coupled to the mo…
Characterizing physical and logical errors in a transversal CNOT via cycle error reconstruction
The University of Sydney(悉尼大学);Universität Innsbruck(因斯布鲁克大学);University of Waterloo(滑铁卢大学);Institute for Quantum Computing, University of Waterloo(滑铁卢大学量子计算研究所);RWTH Aachen University(亚琛工业大学);Forschungszentrum Jülich(于利希研究中心);Alpine Quantum Technologies GmbH(阿尔卑斯量子技术有限公司)
Characterizing nonclassical correlations via local quantum Fisher information
为了研究量子关联作为量子精密测量的一种资源,定义了两种基于量子费舍尔信息(QFI)的量子关联量化方法.通过研究Lu等[X. M. Lu,S. Luo,和C. H. Oh,Phys Rev. A 86,022342(2012)],我们证明了量子关联的存在可以通过由两个层次的测量引起的Fisher信息的差异来确认。特别地,基于QFI的定量量子关联与纯量子态的几何不协调一致。
We present a method for characterizing the performance of noisy quantum processors using discrete time crystals. Deviations from ideal persistent oscillatory behavior give rise to numerical scores by which relative quantum processor capabilities can be measured. We construct small sets of qubit layouts that cover the full topology of a target system, and execute our metric over these sets on a wide range of IBM Quantum processors. We show that there is a large variability in scores, not only across multiple processors, but between different circuit layouts over individual devices. The stabilit…
Quantum resource manipulation may include an ancillary state called a catalyst, which aids the transformation while restoring its original form at the end, and characterizing the enhancement enabled by catalysts is essential to reveal the ultimate manipulability of the precious resource quantity of interest. Here, we show that allowing correlation among multiple catalysts can offer arbitrary power in the manipulation of quantum coherence. We prove that any state transformation can be accomplished with an arbitrarily small error by covariant operations with catalysts that may create a correlati…
Linear optical quantum computing is beset by the lack of deterministic entangling operations besides photon loss. Motivated by advancements at the experimental front in deterministic generation of various kinds of multiphoton entangled states, we propose an architecture for linear-optical quantum computing that harnesses the availability of three-photon Greenberger-Horne-Zeilinger (GHZ) states. Our architecture and its subvariants use polarized photons in GHZ states, polarization beam splitters, delay lines, optical switches and on-off detectors. We concatenate topological quantum error correc…
Characterizing quantum synchronization in the van der Pol oscillator via tomogram and photon correlation
Indian Association for the Cultivation of Science(印度科学文化研究院);The Institute of Mathematical Sciences(数学科学研究所);Government Arts and Science College Kozhikode, University of Calicut(卡利卡特大学科泽科德政府文理科学院);Government College Malappuram, University of Calicut(卡利卡特大学马拉普兰政府学院)
The security of code based constructions is usually assessed by Information Set Decoding (ISD) algorithms. In the quantum setting, amplitude amplification yields an asymptotic square root gain over the classical analogue. However, it is still unclear whether a real quantum circuit could yield actual improvements or suffer an enormous overhead due to its implementation. This leads to different considerations of these quantum attacks in the security analysis of code based proposals. In this work we clarify this doubt by giving the first quantum circuit design of the fully-fledged ISD procedure, …
Entanglement recycling in two-step port-based teleportation
University of Wrocław(弗罗茨瓦夫大学);QuSoft, Amsterdam, The Netherlands(荷兰阿姆斯特丹 QuSoft);Institute for Logic, Language, and Computation, University of Amsterdam(阿姆斯特丹大学逻辑、语言与计算研究所);Korteweg-de Vries Institute for Mathematics, University of Amsterdam(阿姆斯特丹大学科特韦格-德弗里斯数学研究所);Centrum Wiskunde & Informatica (CWI)(数学与计算机科学中心 (CWI));International Centre for Theory of Quantum Technologies (ICTQT), University of Gdańsk(格但斯克大学量子技术理论国际中心 (ICTQT))