Yu-Ao Chen, Xia Liu, Chenghong Zhu, Lei Zhang, Junyu Liu, Xin Wang
Establishing a fully functional quantum internet relies on the efficient allocation of multipartite entangled states, which enables advanced quantum communication protocols, secure multipartite quantum key distribution, and distributed quantum computing. In this work, we propose local operations and classical communication (LOCC) protocols for allocating generalized $N$-qubit W and GHZ states within a centralized hub architecture, where the central hub node preshares Bell states with each end node. Our protocols deterministically and exactly distribute these states using only $N$ qubits of quantum memory within the central system, with communication costs of $2N - 2$ and $N$ classical bits for W and GHZ states, respectively. These resource-efficient protocols are further proven to be optimal within the centralized hub architecture, outperforming conventional teleportation protocols for entanglement distribution in both memory and communication costs. Our results provide a more resource-efficient method for allocating essential multipartite entangled states in quantum networks, paving the way for the realization of a quantum internet with enhanced efficiency.
{"title":"Quantum Entanglement Allocation through a Central Hub","authors":"Yu-Ao Chen, Xia Liu, Chenghong Zhu, Lei Zhang, Junyu Liu, Xin Wang","doi":"arxiv-2409.08173","DOIUrl":"https://doi.org/arxiv-2409.08173","url":null,"abstract":"Establishing a fully functional quantum internet relies on the efficient\u0000allocation of multipartite entangled states, which enables advanced quantum\u0000communication protocols, secure multipartite quantum key distribution, and\u0000distributed quantum computing. In this work, we propose local operations and\u0000classical communication (LOCC) protocols for allocating generalized $N$-qubit W\u0000and GHZ states within a centralized hub architecture, where the central hub\u0000node preshares Bell states with each end node. Our protocols deterministically\u0000and exactly distribute these states using only $N$ qubits of quantum memory\u0000within the central system, with communication costs of $2N - 2$ and $N$\u0000classical bits for W and GHZ states, respectively. These resource-efficient\u0000protocols are further proven to be optimal within the centralized hub\u0000architecture, outperforming conventional teleportation protocols for\u0000entanglement distribution in both memory and communication costs. Our results\u0000provide a more resource-efficient method for allocating essential multipartite\u0000entangled states in quantum networks, paving the way for the realization of a\u0000quantum internet with enhanced efficiency.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202222","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}
We present a novel quantum circuit that genuinely implements the Scully-Dr"uhl-type delayed-choice quantum eraser, where the two recorders of the which-way information directly interact with the signal qubit and remain spatially separated. Experiments conducted on IBM Quantum and IonQ processors demonstrate that the recovery of interference patterns, to varying degrees, aligns closely with theoretical predictions, despite the presence of systematic errors. This quantum circuit-based approach, more manageable and versatile than traditional optical experiments, facilitates arbitrary adjustment of the erasure and enables a true random choice in a genuine delayed-choice manner. On the IBM Quantum platform, delay gates can be employed to further defer the random choice, thereby amplifying the retrocausal effect. Since gate operations are executed sequentially in time, the system does not have any involvement of random choice until after the signal qubit has been measured, therefore eliminating any potential philosophical loopholes regarding retrocausality that might exist in other experimental setups. Remarkably, quantum erasure is achieved with delay times up to $sim1,mutext{s}$ without noticeable decoherence, a feat challenging to replicate in optical setups.
我们提出了一种新型量子电路，它真正实现了斯cully-Dr"uhl 型延迟选择量子擦除器，其中两个方向信息记录器直接与信号量子比特相互作用，并保持空间上的分离。在 IBM 量子和 IonQ 处理器上进行的实验表明，尽管存在系统误差，但干扰模式的恢复在不同程度上与理论预测非常吻合。这种基于量子电路的方法比传统的光学实验更易于管理，用途更广，便于任意调整测量值，并能以真正的延迟选择方式实现真正的随机选择。在 IBM 量子平台上，可以使用延迟门来进一步延迟随机选择，从而放大回溯效应。由于门操作是在时间上按顺序执行的，因此系统在测量信号量子比特之前不会涉及任何随机选择，从而消除了其他实验装置中可能存在的有关逆因性的潜在哲学漏洞。值得注意的是，量子擦除的延迟时间可达$sim1mutext{s}$，而不会注意到相干性，这在光学装置中是难以复制的。
{"title":"Demonstration of Scully-Drühl-type quantum erasers on quantum computers","authors":"Bo-Hung Chen, Dah-Wei Chiou, Hsiu-Chuan Hsu","doi":"arxiv-2409.08053","DOIUrl":"https://doi.org/arxiv-2409.08053","url":null,"abstract":"We present a novel quantum circuit that genuinely implements the\u0000Scully-Dr\"uhl-type delayed-choice quantum eraser, where the two recorders of\u0000the which-way information directly interact with the signal qubit and remain\u0000spatially separated. Experiments conducted on IBM Quantum and IonQ processors\u0000demonstrate that the recovery of interference patterns, to varying degrees,\u0000aligns closely with theoretical predictions, despite the presence of systematic\u0000errors. This quantum circuit-based approach, more manageable and versatile than\u0000traditional optical experiments, facilitates arbitrary adjustment of the\u0000erasure and enables a true random choice in a genuine delayed-choice manner. On\u0000the IBM Quantum platform, delay gates can be employed to further defer the\u0000random choice, thereby amplifying the retrocausal effect. Since gate operations\u0000are executed sequentially in time, the system does not have any involvement of\u0000random choice until after the signal qubit has been measured, therefore\u0000eliminating any potential philosophical loopholes regarding retrocausality that\u0000might exist in other experimental setups. Remarkably, quantum erasure is\u0000achieved with delay times up to $sim1,mutext{s}$ without noticeable\u0000decoherence, a feat challenging to replicate in optical setups.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202227","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}
Ming-Zhi Chung, Andreas Thomasen, Henry Liao, Ryosuke Imai
In this review, we give an overview of the proposed applications in the early-FTQC (EFTQC) era. Starting from the error correction architecture for EFTQC device, we first review the recently developed space-time efficient analogue rotation (STAR) architecture cite{akahoshiPartiallyFaultTolerantQuantum2024}, which is a partially fault-tolerant error correction architecture. Then, we review the requirements of an EFTQC algorithm. In particular, the class of ground state energy estimation (GSEE) algorithm known as the statistical phase estimation algorithm (SPE) is studied. We especially cast our attention on two SPE-type algorithms, the step-function filter-based variant by Lin and Tong (LT22) cite{Lin:2021rwb} and Gaussian Filter cite{Wang:2022gxu}. Based on the latter, we introduce the Gaussian Fitting algorithm, which uses an alternative post-processing procedure compared to cite{Wang:2022gxu}. Finally, we systematically simulate the aforementioned algorithms and Variational Quantum Eigensolver (VQE) using the 1-uCJ ansatz with different shot counts. Most importantly, we perform noisy simulations based on the STAR architecture. We find that for estimating the ground state energy of the 4-qubit $H_2$ Hamiltonian in the STO-3G basis, SPE becomes more advantageous over VQE when the physical error rate is sufficiently low.
{"title":"Contrasting Statistical Phase Estimation with the Variational Quantum Eigensolver in the era of Early Fault Tolerant Quantum Computation","authors":"Ming-Zhi Chung, Andreas Thomasen, Henry Liao, Ryosuke Imai","doi":"arxiv-2409.07749","DOIUrl":"https://doi.org/arxiv-2409.07749","url":null,"abstract":"In this review, we give an overview of the proposed applications in the\u0000early-FTQC (EFTQC) era. Starting from the error correction architecture for EFTQC device, we first\u0000review the recently developed space-time efficient analogue rotation (STAR)\u0000architecture cite{akahoshiPartiallyFaultTolerantQuantum2024}, which is a\u0000partially fault-tolerant error correction architecture. Then, we review the requirements of an EFTQC algorithm. In particular, the class of ground state energy estimation (GSEE) algorithm\u0000known as the statistical phase estimation algorithm (SPE) is studied. We especially cast our attention on two SPE-type algorithms, the\u0000step-function filter-based variant by Lin and Tong (LT22) cite{Lin:2021rwb}\u0000and Gaussian Filter cite{Wang:2022gxu}. Based on the latter, we introduce the Gaussian Fitting algorithm, which uses\u0000an alternative post-processing procedure compared to cite{Wang:2022gxu}. Finally, we systematically simulate the aforementioned algorithms and\u0000Variational Quantum Eigensolver (VQE) using the 1-uCJ ansatz with different\u0000shot counts. Most importantly, we perform noisy simulations based on the STAR\u0000architecture. We find that for estimating the ground state energy of the 4-qubit $H_2$\u0000Hamiltonian in the STO-3G basis, SPE becomes more advantageous over VQE when\u0000the physical error rate is sufficiently low.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202256","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}
Annika S. Wiening, Joern Bergendahl, Vicente Leyton-Ortega, Peter Nalbach
In the burgeoning field of quantum computing, the precise design and optimization of quantum pulses are essential for enhancing qubit operation fidelity. This study focuses on refining the pulse engineering techniques for superconducting qubits, employing a detailed analysis of Square and Gaussian pulse envelopes under various approximation schemes. We evaluated the effects of coherent errors induced by naive pulse designs. We identified the sources of these errors in the Hamiltonian model's approximation level. We mitigated these errors through adjustments to the external driving frequency and pulse durations, thus, implementing a pulse scheme with stroboscopic error reduction. Our results demonstrate that these refined pulse strategies improve performance and reduce coherent errors. Moreover, the techniques developed herein are applicable across different quantum architectures, such as ion-trap, atomic, and photonic systems.
{"title":"Optimizing Qubit Control Pulses for State Preparation","authors":"Annika S. Wiening, Joern Bergendahl, Vicente Leyton-Ortega, Peter Nalbach","doi":"arxiv-2409.08204","DOIUrl":"https://doi.org/arxiv-2409.08204","url":null,"abstract":"In the burgeoning field of quantum computing, the precise design and\u0000optimization of quantum pulses are essential for enhancing qubit operation\u0000fidelity. This study focuses on refining the pulse engineering techniques for\u0000superconducting qubits, employing a detailed analysis of Square and Gaussian\u0000pulse envelopes under various approximation schemes. We evaluated the effects\u0000of coherent errors induced by naive pulse designs. We identified the sources of\u0000these errors in the Hamiltonian model's approximation level. We mitigated these\u0000errors through adjustments to the external driving frequency and pulse\u0000durations, thus, implementing a pulse scheme with stroboscopic error reduction.\u0000Our results demonstrate that these refined pulse strategies improve performance\u0000and reduce coherent errors. Moreover, the techniques developed herein are\u0000applicable across different quantum architectures, such as ion-trap, atomic,\u0000and photonic systems.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"93 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202219","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}
Francesco Monzani, Emanuele Ricci, Luca Nigro, Enrico Prati
We identify a noise model that ensures the functioning of an echo state network employing a gate-based quantum computer for reservoir computing applications. Energy dissipation induced by amplitude damping drastically improves the short-term memory capacity and expressivity of the network, by simultaneously providing fading memory and richer dynamics. There is an ideal dissipation rate that ensures the best operation of the echo state network around $gammasim$ 0.03. Nevertheless, these beneficial effects are stable as the intensity of the applied noise increases. The improvement of the learning is confirmed by emulating a realistic noise model applied to superconducting qubits, paving the way for the application of reservoir computing methods in current non-fault-tolerant quantum computers.
{"title":"Leveraging non-unital noise for gate-based quantum reservoir computing","authors":"Francesco Monzani, Emanuele Ricci, Luca Nigro, Enrico Prati","doi":"arxiv-2409.07886","DOIUrl":"https://doi.org/arxiv-2409.07886","url":null,"abstract":"We identify a noise model that ensures the functioning of an echo state\u0000network employing a gate-based quantum computer for reservoir computing\u0000applications. Energy dissipation induced by amplitude damping drastically\u0000improves the short-term memory capacity and expressivity of the network, by\u0000simultaneously providing fading memory and richer dynamics. There is an ideal\u0000dissipation rate that ensures the best operation of the echo state network\u0000around $gammasim$ 0.03. Nevertheless, these beneficial effects are stable as\u0000the intensity of the applied noise increases. The improvement of the learning\u0000is confirmed by emulating a realistic noise model applied to superconducting\u0000qubits, paving the way for the application of reservoir computing methods in\u0000current non-fault-tolerant quantum computers.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"401 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202251","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}
Jinbing Hu, Kai Zhou, Tianle Song, Xuntao Jiang, Songlin Zhuang, Yi Yang
Momentum-space nonsymmorphic symmetries, stemming from the projective algebra of synthetic gauge fields, can modify the manifold of the Brillouin zone and lead to a variety of topological phenomena. We present an acoustic realization of higher-order topological insulators (HOTIs) protected by a pair of anticommutative momentum-space glide reflections. We confirm the presence of momentum-space glide reflection from the measured momentum half translation of edge bands and their momentum-resolved probability distribution using a cylinder geometry made of acoustic resonator arrays. In particular, we observe both intrinsic and extrinsic HOTI features in such a cylinder: hopping strength variation along the open boundary leads to a bulk gap closure, while that along the closed boundary results in an edge gap closure. In addition, we confirm the presence of quadrupole corner modes with transmission and field distribution measurements. Our observation enriches the study of topological physics of momentum-space nonsymmorphic symmetries.
{"title":"Acoustic higher-order topological insulator from momentum-space nonsymmorphic symmetries","authors":"Jinbing Hu, Kai Zhou, Tianle Song, Xuntao Jiang, Songlin Zhuang, Yi Yang","doi":"arxiv-2409.08196","DOIUrl":"https://doi.org/arxiv-2409.08196","url":null,"abstract":"Momentum-space nonsymmorphic symmetries, stemming from the projective algebra\u0000of synthetic gauge fields, can modify the manifold of the Brillouin zone and\u0000lead to a variety of topological phenomena. We present an acoustic realization\u0000of higher-order topological insulators (HOTIs) protected by a pair of\u0000anticommutative momentum-space glide reflections. We confirm the presence of\u0000momentum-space glide reflection from the measured momentum half translation of\u0000edge bands and their momentum-resolved probability distribution using a\u0000cylinder geometry made of acoustic resonator arrays. In particular, we observe\u0000both intrinsic and extrinsic HOTI features in such a cylinder: hopping strength\u0000variation along the open boundary leads to a bulk gap closure, while that along\u0000the closed boundary results in an edge gap closure. In addition, we confirm the\u0000presence of quadrupole corner modes with transmission and field distribution\u0000measurements. Our observation enriches the study of topological physics of\u0000momentum-space nonsymmorphic symmetries.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202282","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}
Y. -T. Cheng, K. -M. Hsieh, B. -Y. Wu, Z. Q. Niu, F. Aziz, Y. -H. Huang, P. Y. Wen, K. -T. Lin, Y. -H. Lin, J. C. Chen, A. F. Kockum, G. -D. Lin, Z. -R. Lin, Y. Lu, I. -C. Hoi
The ability to slow down light at the single-photon level has applications in quantum information processing and other quantum technologies. We demonstrate two methods, both using just a single artificial atom, enabling dynamic control over microwave light velocities in waveguide quantum electrodynamics (waveguide QED). Our methods are based on two distinct mechanisms harnessing the balance between radiative and non-radiative decay rates of a superconducting artificial atom in front of a mirror. In the first method, we tune the radiative decay of the atom using interference effects due to the mirror; in the second method, we pump the atom to control its non-radiative decay through the Autler--Townes effect. When the half the radiative decay rate exceeds the non-radiative decay rate, we observe positive group delay; conversely, dominance of the non-radiative decay rate results in negative group delay. Our results advance signal-processing capabilities in waveguide QED.
在单光子层面减缓光速的能力可应用于量子信息处理和其他量子技术。我们展示了波导量子电动力学（waveguideQED）中动态控制微波光速的两种方法，这两种方法都只使用了一个人造原子。我们的方法基于两种不同的机制，利用镜面前超导人工原子的辐射衰变率和非辐射衰变率之间的平衡。在第一种方法中，我们利用镜子产生的干涉效应来调节原子的辐射衰变；在第二种方法中，我们通过Autler--Townese效应来控制原子的非辐射衰变。当辐射衰变率超过非辐射衰变率的一半时，我们观察到正的群延迟；反之，非辐射衰变率占主导地位会导致负的群延迟。我们的研究结果推进了波导 QED 的信号处理能力。
{"title":"Group delay controlled by the decoherence of a single artificial atom","authors":"Y. -T. Cheng, K. -M. Hsieh, B. -Y. Wu, Z. Q. Niu, F. Aziz, Y. -H. Huang, P. Y. Wen, K. -T. Lin, Y. -H. Lin, J. C. Chen, A. F. Kockum, G. -D. Lin, Z. -R. Lin, Y. Lu, I. -C. Hoi","doi":"arxiv-2409.07731","DOIUrl":"https://doi.org/arxiv-2409.07731","url":null,"abstract":"The ability to slow down light at the single-photon level has applications in\u0000quantum information processing and other quantum technologies. We demonstrate\u0000two methods, both using just a single artificial atom, enabling dynamic control\u0000over microwave light velocities in waveguide quantum electrodynamics (waveguide\u0000QED). Our methods are based on two distinct mechanisms harnessing the balance\u0000between radiative and non-radiative decay rates of a superconducting artificial\u0000atom in front of a mirror. In the first method, we tune the radiative decay of\u0000the atom using interference effects due to the mirror; in the second method, we\u0000pump the atom to control its non-radiative decay through the Autler--Townes\u0000effect. When the half the radiative decay rate exceeds the non-radiative decay\u0000rate, we observe positive group delay; conversely, dominance of the\u0000non-radiative decay rate results in negative group delay. Our results advance\u0000signal-processing capabilities in waveguide QED.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202257","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}
Despite many successes of quantum electrodynamics (QED), we do not presently have a good understanding of this field of physics. QED has all of the foundational problems that standard non-relativistic quantum mechanics has, and further ones in addition. I discuss some of these problems and some options for what a Bohm-style theory of QED, with an ontology in space and time, could look like. I also point out why the proposal made by Bohm himself in 1952 for QED is not quite convincing. Finally, I outline the kind of Bohm-type theory of QED that I would consider convincing, and report about recent progress toward this kind of theory.
尽管量子电动力学（QED）取得了许多成功，但我们目前对这一物理学领域还没有很好的理解。量子电动力学存在标准非相对论量子力学所存在的所有基础问题，此外还有更多问题。我将讨论其中的一些问题，以及具有时空本体论的博姆式 QED 理论的一些方案。我还指出了为什么玻姆本人在 1952 年为 QED 提出的建议不太令人信服。最后，我概述了我认为令人信服的博姆式 QED 理论，并报告了最近朝着这种理论取得的进展。
{"title":"A Vision for a Bohm-Style Theory of Quantum Electrodynamics","authors":"Roderich Tumulka","doi":"arxiv-2409.07784","DOIUrl":"https://doi.org/arxiv-2409.07784","url":null,"abstract":"Despite many successes of quantum electrodynamics (QED), we do not presently\u0000have a good understanding of this field of physics. QED has all of the\u0000foundational problems that standard non-relativistic quantum mechanics has, and\u0000further ones in addition. I discuss some of these problems and some options for\u0000what a Bohm-style theory of QED, with an ontology in space and time, could look\u0000like. I also point out why the proposal made by Bohm himself in 1952 for QED is\u0000not quite convincing. Finally, I outline the kind of Bohm-type theory of QED\u0000that I would consider convincing, and report about recent progress toward this\u0000kind of theory.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202258","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}
Ilhwan Kim, Yosep Kim, Yong-Su Kim, Kwang Jo Lee, Hyang-Tag Lim
Entangled photon sources are essential for quantum information applications, including quantum computation, quantum communication, and quantum metrology. Periodically poled (PP) crystals are commonly used to generate bright photon sources through quasi-phase matching. However, fabricating uniform micron-scale periodic structures poses significant technical difficulties, typically limiting the crystal thickness to less than a millimeter. Here, we adopt non-critical phase matching to produce a robust and bright polarization-entangled photon source based on a Sagnac interferometer. This method is tolerant of variations in pump incidence angles and temperature, and theoretically offers about a 2.5-fold brightness enhancement compared to quasi-phase matching. Additionally, the absence of periodic poling allows for a larger crystal cross-section. Using a bulk KTP crystal without a PP structure, we experimentally produce the four Bell states with a brightness of 25.1 kHz/mW, achieving purity, concurrence, and fidelity values close to 0.99. We believe our scheme will serve as a key building block for scalable and practical photonic quantum information applications.
{"title":"Robust and bright polarization-entangled photon sources exploiting non-critical phase matching without periodic poling","authors":"Ilhwan Kim, Yosep Kim, Yong-Su Kim, Kwang Jo Lee, Hyang-Tag Lim","doi":"arxiv-2409.07673","DOIUrl":"https://doi.org/arxiv-2409.07673","url":null,"abstract":"Entangled photon sources are essential for quantum information applications,\u0000including quantum computation, quantum communication, and quantum metrology.\u0000Periodically poled (PP) crystals are commonly used to generate bright photon\u0000sources through quasi-phase matching. However, fabricating uniform micron-scale\u0000periodic structures poses significant technical difficulties, typically\u0000limiting the crystal thickness to less than a millimeter. Here, we adopt\u0000non-critical phase matching to produce a robust and bright\u0000polarization-entangled photon source based on a Sagnac interferometer. This\u0000method is tolerant of variations in pump incidence angles and temperature, and\u0000theoretically offers about a 2.5-fold brightness enhancement compared to\u0000quasi-phase matching. Additionally, the absence of periodic poling allows for a\u0000larger crystal cross-section. Using a bulk KTP crystal without a PP structure,\u0000we experimentally produce the four Bell states with a brightness of 25.1\u0000kHz/mW, achieving purity, concurrence, and fidelity values close to 0.99. We\u0000believe our scheme will serve as a key building block for scalable and\u0000practical photonic quantum information applications.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202259","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}
Manuel Calixto, Alberto Mayorgas, Octavio Castaños
Zero energy eigenstates $psi_0(theta)$ of the twisted bilayer graphene Hamiltonian at the Dirac point show a high sensitivity to the twist angle $theta$ near the magic angles where the effective Fermi velocity vanishes. We use information theory markers, like fidelity-susceptibility and entanglement entropy of the reduced density matrix to the layer sector, to capture this quantum criticality of zero modes at magic twist angles.
{"title":"Capturing magic angles in twisted bilayer graphene from information theory markers","authors":"Manuel Calixto, Alberto Mayorgas, Octavio Castaños","doi":"arxiv-2409.07935","DOIUrl":"https://doi.org/arxiv-2409.07935","url":null,"abstract":"Zero energy eigenstates $psi_0(theta)$ of the twisted bilayer graphene\u0000Hamiltonian at the Dirac point show a high sensitivity to the twist angle\u0000$theta$ near the magic angles where the effective Fermi velocity vanishes. We\u0000use information theory markers, like fidelity-susceptibility and entanglement\u0000entropy of the reduced density matrix to the layer sector, to capture this\u0000quantum criticality of zero modes at magic twist angles.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202286","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：