Quantum最新文献 - Book学术

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-04-24 DOI: 10.22331/q-2025-04-24-1721

Vittorio D'Esposito, Giuseppe Fabiano, Domenico Frattulillo, Flavio Mercati

{"title":"Doubly Quantum Mechanics","authors":"Vittorio D'Esposito, Giuseppe Fabiano, Domenico Frattulillo, Flavio Mercati","doi":"10.22331/q-2025-04-24-1721","DOIUrl":"https://doi.org/10.22331/q-2025-04-24-1721","url":null,"abstract":"Motivated by the expectation that relativistic symmetries might acquire quantum features in Quantum Gravity, we take the first steps towards a theory of ''Doubly'' Quantum Mechanics, a modification of Quantum Mechanics in which the geometrical configurations of physical systems, measurement apparata, and reference frame transformations are themselves quantized and described by ''geometry'' states in a Hilbert space. We develop the formalism for spin-$frac{1}{2}$ measurements by promoting the group of spatial rotations $SU(2)$ to the quantum group $SU_q(2)$ and generalizing the axioms of Quantum Theory in a covariant way. As a consequence of our axioms, the notion of probability becomes a self-adjoint operator acting on the Hilbert space of geometry states, hence acquiring novel non-classical features. After introducing a suitable class of semi-classical geometry states, which describe near-to-classical geometrical configurations of physical systems, we find that probability measurements are affected, in these configurations, by intrinsic uncertainties stemming from the quantum properties of $SU_q(2)$. This feature translates into an unavoidable fuzziness for observers attempting to align their reference frames by exchanging qubits, even when the number of exchanged qubits approaches infinity, contrary to the standard $SU(2)$ case.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"1 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143872896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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

The Foliage Partition: An Easy-to-Compute LC-Invariant for Graph States 叶分割：一个易于计算的图状态的lc不变量

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-04-24 DOI: 10.22331/q-2025-04-24-1720

Adam Burchardt, Frederik Hahn

引用次数: 0

SuperGrad: a differentiable simulator for superconducting processors SuperGrad：超导处理器的可微分模拟器

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-04-24 DOI: 10.22331/q-2025-04-24-1722

Ziang Wang, Feng Wu, Hui-Hai Zhao, Xin Wan, Xiaotong Ni

引用次数: 0

Quantum dynamics as a pseudo-density matrix 伪密度矩阵的量子动力学

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-04-24 DOI: 10.22331/q-2025-04-24-1719

James Fullwood

引用次数: 0

Alternatives of entanglement depth and metrological entanglement criteria 可选择的纠缠深度和计量纠缠标准

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-04-18 DOI: 10.22331/q-2025-04-18-1718

Szilárd Szalay, Géza Tóth

{"title":"Alternatives of entanglement depth and metrological entanglement criteria","authors":"Szilárd Szalay, Géza Tóth","doi":"10.22331/q-2025-04-18-1718","DOIUrl":"https://doi.org/10.22331/q-2025-04-18-1718","url":null,"abstract":"We work out the general theory of one-parameter families of partial entanglement properties and the resulting entanglement depth-like quantities. Special cases of these are the depth of partitionability, the depth of producibility (or simply entanglement depth) and the depth of stretchability, which are based on one-parameter families of partial entanglement properties known earlier. We also construct some further physically meaningful properties, for instance the squareability, the toughness, the degree of freedom, and also several ones of entropic motivation. Metrological multipartite entanglement criteria with the quantum Fisher information fit naturally into this framework. Here we formulate these for the depth of squareability, which therefore turns out to be the natural choice, leading to stronger bounds than the usual entanglement depth. Namely, the quantum Fisher information turns out to provide a lower bound not only on the maximal size of entangled subsystems, but also on the average size of entangled subsystems for a random choice of elementary subsystems. We also formulate criteria with convex quantities for both cases, which are much stronger than the original ones. In particular, the quantum Fisher information puts a lower bound on the average size of entangled subsystems. We also argue that one-parameter partial entanglement properties, which carry entropic meaning, are more suitable for the purpose of defining metrological bounds.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"30 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143847270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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

Lossy-and-Constrained Extended Non-Local Games with Applications to Quantum Cryptography 损耗约束扩展非局部对策在量子密码学中的应用

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-04-18 DOI: 10.22331/q-2025-04-18-1712

Llorenç Escolà-Farràs, Florian Speelman

引用次数: 0

Lower Bounds for Unitary Property Testing with Proofs and Advice 酉性检验的下界及其证明和建议

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-04-18 DOI: 10.22331/q-2025-04-18-1717

Jordi Weggemans

{"title":"Lower Bounds for Unitary Property Testing with Proofs and Advice","authors":"Jordi Weggemans","doi":"10.22331/q-2025-04-18-1717","DOIUrl":"https://doi.org/10.22331/q-2025-04-18-1717","url":null,"abstract":"In unitary property testing a quantum algorithm, also known as a tester, is given query access to a black-box unitary and has to decide whether it satisfies some property. We propose a new technique for proving lower bounds on the quantum query complexity of unitary property testing and related problems, which utilises its connection to unitary channel discrimination. The main advantage of this technique is that all obtained lower bounds hold for any $mathsf{C}$-tester with $mathsf{C} subseteq mathsf{QMA}(2)/mathsf{qpoly}$, showing that even having access to both (unentangled) quantum proofs and advice does not help for many unitary property testing problems. We apply our technique to prove lower bounds for problems like quantum phase estimation, the entanglement entropy problem, quantum Gibbs sampling and more, removing all logarithmic factors in the lower bounds obtained by the sample-to-query lifting theorem of Wang and Zhang (2023). As a direct corollary, we show that there exist quantum oracles relative to which $mathsf{QMA}(2) notsupset mathsf{SBQP}$ and $mathsf{QMA}/mathsf{qpoly} notsupset mathsf{SBQP}$. The former shows that, at least in a black-box way, having unentangled quantum proofs does not help in solving problems that require high precision.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"50 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143847198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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

$mathcal{PT}$-symmetric mapping of three states and its implementation on a cloud quantum processor $mathcal{PT}$-三态对称映射及其在云量子处理器上的实现

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-04-18 DOI: 10.22331/q-2025-04-18-1716

Yaroslav Balytskyi, Yevgen Kotukh, Gennady Khalimov, Sang-Yoon Chang

{"title":"$mathcal{PT}$-symmetric mapping of three states and its implementation on a cloud quantum processor","authors":"Yaroslav Balytskyi, Yevgen Kotukh, Gennady Khalimov, Sang-Yoon Chang","doi":"10.22331/q-2025-04-18-1716","DOIUrl":"https://doi.org/10.22331/q-2025-04-18-1716","url":null,"abstract":"$mathcal{PT}$-symmetric systems have garnered significant attention due to their unconventional properties. Despite the growing interest, there remains an ongoing debate about whether these systems outperform their Hermitian counterparts in practical applications, and if so, by what metrics this performance should be measured. We developed $mathcal{PT}$-symmetric approach for mapping $N = 3$ pure qubit states to address this, implemented it using the dilation method, and demonstrated it on a superconducting quantum processor from the IBM Quantum Experience. For the first time, we derived exact expressions for the population of the post-selected $mathcal{PT}$-symmetric subspace for both $N = 2$ and $N = 3$ states. When applied to the discrimination of $N = 2$ pure states, our algorithm provides an equivalent result to the conventional unambiguous quantum state discrimination. For $N = 3$ states, our approach introduces novel capabilities not available in traditional Hermitian systems, enabling the transformation of an arbitrary set of three pure quantum states into another, at the cost of introducing an inconclusive outcome. Our algorithm has the same error rate for the attack on the three-state QKD protocol as the conventional minimum error, maximum confidence, and maximum mutual information strategies. For post-selected quantum metrology, our results provide precise conditions where $mathcal{PT}$-symmetric quantum sensors outperform their Hermitian counterparts in terms of information-cost rate. Combined with punctuated unstructured quantum database search, our method significantly reduces the qubit readout requirements at the cost of adding an ancilla, while maintaining the same average number of oracle calls as the original punctuated Grover's algorithm. Our work opens new pathways for applying $mathcal{PT}$ symmetry in quantum communications, computing, and cryptography.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"104 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143847197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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

Interferometric binary phase estimations 干涉二元相位估计

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-04-18 DOI: 10.22331/q-2025-04-18-1713

Simone Roncallo, Xi Lu, Lorenzo Maccone

引用次数: 0

Optimal sampling of tensor networks targeting wave function’s fast decaying tails 针对波函数快速衰减尾的张量网络的最优采样

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-04-18 DOI: 10.22331/q-2025-04-18-1714

Marco Ballarin, Pietro Silvi, Simone Montangero, Daniel Jaschke

引用次数: 0