{"title":"Krylov Expressivity in Quantum Reservoir Computing and Quantum Extreme Learning","authors":"Saud Čindrak, Lina Jaurigue, Kathy Lüdge","doi":"arxiv-2409.12079","DOIUrl":"https://doi.org/arxiv-2409.12079","url":null,"abstract":"Quantum machine learning utilizes the high-dimensional space of quantum\u0000systems, attracting significant research interest. This study employs Krylov\u0000complexity to analyze task performance in quantum machine learning. We\u0000calculate the spread complexity and effective dimension of the Krylov space,\u0000introducing the effective dimension as an easy-to-compute, measurable, and\u0000upper-bounded expressivity measure. Our analysis covers quantum reservoir\u0000computers and quantum extreme learning machines, showing that increasing\u0000effective dimension correlates with improved performance. We validate this with\u0000the Lorenz cross-prediction task, observing reduced error with higher effective\u0000dimensions. Lastly, we compare the spread complexity, the effective dimension,\u0000and the fidelity as expressivity measures and show that fidelity is not\u0000suitable, while spread complexity can qualitatively explain task performance.\u0000Only the effective dimension captures the phase space accurately and exhibits\u0000the same saturation as task performance for similar evolution times.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"53 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Quantum jumps in amplitude bistability: tracking a coherent and invertible state localization","authors":"Th. K. Mavrogordatos","doi":"arxiv-2409.11260","DOIUrl":"https://doi.org/arxiv-2409.11260","url":null,"abstract":"We investigate the nature of quantum jumps occurring between macroscopic\u0000metastable states of light in the open driven Jaynes-Cummings model. We find\u0000that, in the limit of zero spontaneous emission considered in [H. J.\u0000Carmichael, Phys. Rev. X 5, 031028 (2015)], the jumps from a high-photon state\u0000to the vacuum state entail two stages. The first part is coherent and modelled\u0000by the localization of a state superposition, in the example of a\u0000null-measurement record predicted by quantum trajectory theory. The underlying\u0000evolution is mediated by an unstable state (which often splits to a complex of\u0000states), identified by the conditioned density matrix and the corresponding\u0000quasiprobability distribution of the cavity field. The unstable state\u0000subsequently decays to the vacuum to complete the jump. Coherence in the\u0000localization allows for inverting the null-measurement photon average about its\u0000initial value, to account for the full switch which typically lasts a small\u0000fraction of the cavity lifetime. This mechanism is contrasted to the jumps\u0000leading from the vacuum to the high-photon state in the bistable signal.\u0000Spontaneous emission degrades coherence in the localization, and prolongs the\u0000jumps.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Crosscap states and duality of Ising field theory in two dimensions","authors":"Yueshui Zhang, Ying-Hai Wu, Lei Wang, Hong-Hao Tu","doi":"arxiv-2409.11046","DOIUrl":"https://doi.org/arxiv-2409.11046","url":null,"abstract":"We propose two distinct crosscap states for the two-dimensional (2D) Ising\u0000field theory. These two crosscap states, identifying Ising spins or dual spins\u0000(domain walls) at antipodal points, are shown to be related via the\u0000Kramers-Wannier duality transformation. We derive their Majorana free field\u0000representations and extend bosonization techniques to calculate correlation\u0000functions of the 2D Ising conformal field theory (CFT) with different crosscap\u0000boundaries. We further develop a conformal perturbation theory to calculate the\u0000Klein bottle entropy as a universal scaling function [Phys. Rev. Lett. 130,\u0000151602 (2023)] in the 2D Ising field theory. The formalism developed in this\u0000work is applicable to many other 2D CFTs perturbed by relevant operators.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A short trajectory is all you need: A transformer-based model for long-time dissipative quantum dynamics","authors":"Luis E. Herrera Rodríguez, Alexei A. Kananenka","doi":"arxiv-2409.11320","DOIUrl":"https://doi.org/arxiv-2409.11320","url":null,"abstract":"In this communication we demonstrate that a deep artificial neural network\u0000based on a transformer architecture with self-attention layers can predict the\u0000long-time population dynamics of a quantum system coupled to a dissipative\u0000environment provided that the short-time population dynamics of the system is\u0000known. The transformer neural network model developed in this work predicts the\u0000long-time dynamics of spin-boson model efficiently and very accurately across\u0000different regimes, from weak system-bath coupling to strong coupling\u0000non-Markovian regimes. Our model is more accurate than classical forecasting\u0000models, such as recurrent neural networks and is comparable to the\u0000state-of-the-art models for simulating the dynamics of quantum dissipative\u0000systems, based on kernel ridge regression.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A quantum protocol for applying arbitrary phase transformations","authors":"Siavash Davani, Falk Eilenberger","doi":"arxiv-2409.11020","DOIUrl":"https://doi.org/arxiv-2409.11020","url":null,"abstract":"Given an operator that produces the state\u0000$|phirangle=sumphi(x),|xrangle$, we propose a quantum protocol that\u0000transforms any input state of the form $|psirangle=sumpsi(x),|xrangle$ to\u0000$|psi'rangle=sumpsi(x),e^{ialpha|phi(x)|^2},|xrangle$. This protocol\u0000is thus programmable in the sense that one can use it to apply different phase\u0000profiles $e^{ialpha|phi(x)|^2}$ by choosing different $|phirangle$ states\u0000as the input parameter at each run. Therefore, the problem of applying phases\u0000to a signal via a quantum computer is reduced to the problem of initializing a\u0000state $|phirangle$ that corresponds to the desired phase profile.\u0000Furthermore, we discuss possible applications of this protocol, most\u0000importantly in Hamiltonian simulation.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Harvesting magic from the vacuum","authors":"Ron Nyström, Nicola Pranzini, Esko Keski-Vakkuri","doi":"arxiv-2409.11473","DOIUrl":"https://doi.org/arxiv-2409.11473","url":null,"abstract":"Magic is the quantum resource allowing a quantum computer to perform\u0000operations that cannot be simulated efficiently by classical computation. As\u0000such, generating magic in a quantum system is crucial for achieving quantum\u0000advantage. This letter shows that magic can be harvested by a three-level\u0000Unruh-DeWitt detector (a qutrit) interacting with a quantum field in an initial\u0000vacuum state. While the idea of extracting resources from Quantum Field\u0000Theories (QFT) was born from the harvesting of entanglement, our result extends\u0000the protocol to evolve a qutrit from a non-magical state to a magical one,\u0000making it possible to generate magic from QFT.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Dynamical topological phase transition in cold Rydberg quantum gases","authors":"Jun Zhang, Ya-Jun Wang, Bang Liu, Li-Hua Zhang, Zheng-Yuan Zhang, Shi-Yao Shao, Qing Li, Han-Chao Chen, Yu Ma, Tian-Yu Han, Qi-Feng Wang, Jia-Dou Nan, Yi-Ming Yin, Dong-Yang Zhu, Bao-Sen Shi, Dong-Sheng Ding","doi":"arxiv-2409.11035","DOIUrl":"https://doi.org/arxiv-2409.11035","url":null,"abstract":"Study of phase transitions provide insights into how a many-body system\u0000behaves under different conditions, enabling us to understand the symmetry\u0000breaking, critical phenomena, and topological properties. Strong long-range\u0000interactions in highly excited Rydberg atoms create a versatile platform for\u0000exploring exotic emergent topological phases. Here, we report the experimental\u0000observation of dynamical topological phase transitions in cold Rydberg atomic\u0000gases under a microwave field driving. By measuring the system transmission\u0000curves while varying the probe intensity, we observe complex hysteresis\u0000trajectories characterized by distinct winding numbers as they cross the\u0000critical point. At the transition state, where the winding number flips, the\u0000topology of these hysteresis trajectories evolves into more non-trivial\u0000structures. The topological trajectories are shown to be robust against noise,\u0000confirming their rigidity in dynamic conditions. These findings contribute to\u0000the insights of emergence of complex dynamical topological phases in many-body\u0000systems.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Multipartite entanglement vs nonlocality for two families of $N$-qubit states","authors":"Sanchit Srivastava, Shohini Ghose","doi":"arxiv-2409.10888","DOIUrl":"https://doi.org/arxiv-2409.10888","url":null,"abstract":"Quantum states of multiple qubits can violate Bell-type inequalities when\u0000there is entanglement present between the qubits, indicating nonlocal behaviour\u0000of correlations. We analyze the relation between multipartite entanglement and\u0000genuine multipartite nonlocality, characterized by Svetlichny inequality\u0000violations, for two families of $N-$qubit states. We show that for the\u0000generalized GHZ family of states, Svetlichny inequality is not violated when\u0000the $n-$tangle is less than $1/2$ for any number of qubits. On the other hand,\u0000the maximal slice states always violate the Svetlichny inequality when\u0000$n-$tangle is nonzero, and the violation increases monotonically with tangle\u0000when the number of qubits is even. Our work generalizes the relations between\u0000tangle and Svetlichny inequality violation previously derived for three qubits.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yoshisuke Ban, Kimihiko Kato, Shota Iizuka, Hiroshi Oka, Shigenori Murakami, Koji Ishibashi, Satoshi Moriyama, Takahiro Mori, Keiji Ono
{"title":"Pauli spin blockade at room temperature in S/Zn-codoped silicon tunnel field effect transistors","authors":"Yoshisuke Ban, Kimihiko Kato, Shota Iizuka, Hiroshi Oka, Shigenori Murakami, Koji Ishibashi, Satoshi Moriyama, Takahiro Mori, Keiji Ono","doi":"arxiv-2409.10881","DOIUrl":"https://doi.org/arxiv-2409.10881","url":null,"abstract":"Pauli spin blockade (PSB) has been used in fundamental studies on spins in\u0000quantum dots (QDs) and qubit readouts. The operating temperature of PSB is\u0000limited by that of QDs and remains below 10 K, limiting wide application\u0000development. Herein, we confirm that a single deep dopant in the channel of a\u0000field effect transistor functions as a room-temperature QD; consequently,\u0000transport through two different deep dopants exhibits PSB up to room\u0000temperature. The characteristic magnetoconductance provides a means to identify\u0000PSB and enables the PSB device to function as a magnetic sensor with a\u0000sensitivity of <20 uT. Liftings of PSB by magnetic resonance are also observed\u0000at low temperatures. This unique system is expected to realize room-temperature\u0000quantum technologies based on silicon technology.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Several families of entanglement criteria for multipartite quantum systems based on generalized Wigner-Yanase skew information and variance","authors":"Yan Hong, Xinlan Hao, Limin Gao","doi":"arxiv-2409.11273","DOIUrl":"https://doi.org/arxiv-2409.11273","url":null,"abstract":"Quantum entanglement plays a critical role in many quantum applications, but\u0000detecting entanglement, especially in multipartite or high-dimensional quantum\u0000systems, remains a challenge. In this paper, we propose several families of\u0000entanglement criteria for detecting entanglement in multipartite or\u0000high-dimensional quantum states using generalized Wigner-Yanase skew\u0000information and variance. We also reveal a complementary character between the\u0000criteria based on generalized Wigner-Yanase skew information and an alternative\u0000one based on variance through specific examples. We illustrate the merits of\u0000these criteria and show that the combination of the entanglement criteria has a\u0000stronger detection capability, as it is capable of detecting entangled states\u0000that remain unrecognized by other criteria.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}