IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-09-29 DOI: 10.22331/q-2025-09-29-1865

Zhiyao Li, Dorota M. Grabowska, Martin J. Savage

{"title":"Sequency Hierarchy Truncation (SeqHT) for Adiabatic State Preparation and Time Evolution in Quantum Simulations","authors":"Zhiyao Li, Dorota M. Grabowska, Martin J. Savage","doi":"10.22331/q-2025-09-29-1865","DOIUrl":"https://doi.org/10.22331/q-2025-09-29-1865","url":null,"abstract":"We introduce the Sequency Hierarchy Truncation (SeqHT) scheme for reducing the resources required for state preparation and time evolution in quantum simulations, based upon a truncation in sequency. For the $lambdaphi^4$ interaction in scalar field theory, or any interaction with a polynomial expansion, upper bounds on the contributions of operators of a given sequency are derived. For the systems we have examined, observables computed in sequency-truncated wavefunctions, including quantum correlations as measured by magic, are found to step-wise converge to their exact values with increasing cutoff sequency. The utility of SeqHT is demonstrated in the adiabatic state preparation of the $lambdaphi^4$ anharmonic oscillator ground state using IBM's quantum computer $texttt{ibm_sherbrooke}$. Using SeqHT, the depth of the required quantum circuits is reduced by $sim 30%$, leading to significantly improved determinations of observables in the quantum simulations. More generally, SeqHT is expected to lead to a reduction in required resources for quantum simulations of systems with a hierarchy of length scales.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"53 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145182827","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

Hybrid Quantum Cryptography from Communication Complexity 从通信复杂性看混合量子密码

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-09-24 DOI: 10.22331/q-2025-09-24-1862

Francesco Mazzoncini, Balthazar Bauer, Peter Brown, Romain Alléaume

{"title":"Hybrid Quantum Cryptography from Communication Complexity","authors":"Francesco Mazzoncini, Balthazar Bauer, Peter Brown, Romain Alléaume","doi":"10.22331/q-2025-09-24-1862","DOIUrl":"https://doi.org/10.22331/q-2025-09-24-1862","url":null,"abstract":"We introduce an explicit construction for a key distribution protocol in the Quantum Computational Timelock (QCT) security model, where one assumes that computationally secure encryption may only be broken after a time much longer than the coherence time of available quantum memories.<br/> Taking advantage of the QCT assumptions, we build a key distribution protocol called HM-QCT from the Hidden Matching problem for which there exists an exponential gap in one-way communication complexity between classical and quantum strategies.<br/> We establish that the security of HM-QCT against arbitrary i.i.d. attacks can be reduced to the difficulty of solving the underlying Hidden Matching problem with classical information. Legitimate users, on the other hand, can use quantum communication, which gives them the possibility of sending multiple copies of the same quantum state while retaining an information advantage. This leads to an everlasting secure key distribution scheme over $n$ bosonic modes. Such a level of security is unattainable with purely classical techniques. Remarkably, the scheme remains secure with up to $mathcal{O}big( frac{sqrt{n}}{log(n)}big)$ input photons for each channel use, extending the functionalities and potentially outperforming QKD rates by several orders of magnitudes.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"10 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145127580","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

Quantifying spectral signatures of non-Markovianity beyond the Born-Redfield master equation 在Born-Redfield主方程之外量化非马尔可夫性的谱特征

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-09-24 DOI: 10.22331/q-2025-09-24-1863

A. Keefe, N. Agarwal, A. Kamal

{"title":"Quantifying spectral signatures of non-Markovianity beyond the Born-Redfield master equation","authors":"A. Keefe, N. Agarwal, A. Kamal","doi":"10.22331/q-2025-09-24-1863","DOIUrl":"https://doi.org/10.22331/q-2025-09-24-1863","url":null,"abstract":"Memory or time-non-local effects in open quantum dynamics pose theoretical as well as practical challenges in the understanding and control of noisy quantum systems. While there has been a comprehensive and concerted effort towards developing diagnostics for non-Markovian dynamics, all existing measures rely on time-domain measurements which are typically slow and expensive as they require averaging several runs to resolve small transient features on a broad background, and scale unfavorably with system size and complexity. In this work, we propose a spectroscopic measure of non-Markovianity which can detect persistent non-Markovianity in the system steady state. In addition to being experimentally viable, the proposed measure has a direct information theoretic interpretation: a large value indicates the information loss per unit bandwidth of making the Markov approximation. In the same vein, we derive a frequency-domain quantum master equation (FD-QME) that goes beyond the standard Born-Redfield description and retains the full memory of the state of the reduced system. Using the FD-QME and the proposed measure, we are able to reliably diagnose and quantify non-Markovianity in several system-environment settings including those with environmental correlations and retardation effects.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"2 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145127681","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

Adaptivity is not helpful for Pauli channel learning 自适应对泡利通道学习没有帮助

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-09-24 DOI: 10.22331/q-2025-09-24-1864

Xuan Du Trinh, Nengkun Yu

引用次数: 0

Topological, multi-mode amplification induced by non-reciprocal, long-range dissipative couplings 拓扑，多模放大诱导非互易，远程耗散耦合

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-09-18 DOI: 10.22331/q-2025-09-18-1861

Carlos Vega, Alberto Muñoz de las Heras, Diego Porras, Alejandro González-Tudela

引用次数: 0

Lower T-count with faster algorithms 使用更快的算法降低t计数

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-09-16 DOI: 10.22331/q-2025-09-16-1860

Vivien Vandaele

{"title":"Lower T-count with faster algorithms","authors":"Vivien Vandaele","doi":"10.22331/q-2025-09-16-1860","DOIUrl":"https://doi.org/10.22331/q-2025-09-16-1860","url":null,"abstract":"Among the cost metrics characterizing a quantum circuit, the $T$-count stands out as one of the most crucial as its minimization is particularly important in various areas of quantum computation such as fault-tolerant quantum computing and quantum circuit simulation. In this work, we contribute to the $T$-count reduction problem by proposing efficient $T$-count optimizers with low execution times. In particular, we greatly improve the complexity of TODD, an algorithm currently providing the best $T$-count reduction on various quantum circuits. We also propose some modifications to the algorithm which are leading to a significantly lower number of $T$ gates. In addition, we propose another algorithm which has an even lower complexity and that achieves a better or equal $T$-count than the state of the art on most quantum circuits evaluated. We also prove that the number of $T$ gates in the circuit obtained after executing our algorithms on a Hadamard-free circuit composed of $n$ qubits is upper bounded by $n(n + 1)/2 + 1$, which improves on the worst-case $T$-count of existing optimization algorithms. From this we derive an upper bound of $(n + 1)(n + 2h)/2 + 1$ for the number of $T$ gates in a Clifford$+T$ circuit where $h$ is the number of internal Hadamard gates in the circuit, i.e. the number of Hadamard gates lying between the first and the last $T$ gate of the circuit.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"15 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145068057","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

Loschmidt echo, emerging dual unitarity and scaling of generalized temporal entropies after quenches to the critical point 洛施密特回声，出现对偶性和广义时间熵在淬灭到临界点后的标度

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-09-16 DOI: 10.22331/q-2025-09-16-1859

Stefano Carignano, Luca Tagliacozzo

引用次数: 0

From Magic State Distillation to Dynamical Systems 从神奇状态蒸馏到动力系统

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-09-15 DOI: 10.22331/q-2025-09-15-1858

Yunzhe Zheng, Dong E. Liu

{"title":"From Magic State Distillation to Dynamical Systems","authors":"Yunzhe Zheng, Dong E. Liu","doi":"10.22331/q-2025-09-15-1858","DOIUrl":"https://doi.org/10.22331/q-2025-09-15-1858","url":null,"abstract":"Magic State Distillation (MSD) has been a research focus for fault-tolerant quantum computing due to the need for non-Clifford resource in gaining quantum advantage. Although many of the MSD protocols so far are based on stabilizer codes with transversal $T$ gates, there exists quite several protocols that don't fall into this class. Here we propose a method to map MSD protocols to iterative dynamical systems under the framework of stabilizer reduction. With the proposed mapping, we are able to analyze the performance of MSD protocols using techniques from dynamical systems theory, easily simulate the distillation process of input states under arbitrary noise and visualize it using flow diagram. We apply our mapping to common MSD protocols for $|Trangle$ state and find some interesting properties: The $[[15, 1, 3]]$ code may distill states corresponding to $sqrt{T}$ gate and the $[[5, 1, 3]]$ code can distill the magic state corresponding to the $T$ gate. Besides, we examine the exotic MSD protocols that may distill into other magic states proposed in [Eur. Phys. J. D 70, 55 (2016)] and identify the condition for distillable magic states. We also study new MSD protocols generated by concatenating different codes and numerically demonstrate that concatenation can generate MSD protocols with various magic states. By concatenating efficient codes with exotic codes, we can reduce the overhead of the exotic MSD protocols. We believe our proposed method will be a useful tool for simulating and visualization MSD protocols for canonical MSD protocols on $|Trangle$ as well as other unexplored MSD protocols for other states.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"1 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145059424","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

Nonlocal transfer of high-dimensional unitary operations 高维酉运算的非局部转移

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-09-11 DOI: 10.22331/q-2025-09-11-1855

Dilip Paneru, Francesco Di Colandrea, Alessio D'Errico, Ebrahim Karimi

引用次数: 0

Describing Trotterized Time Evolutions on Noisy Quantum Computers via Static Effective Lindbladians 用静态有效林德布拉迪亚人描述噪声量子计算机上的时域演化

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-09-11 DOI: 10.22331/q-2025-09-11-1854

Keith R. Fratus, Kirsten Bark, Nicolas Vogt, Juha Leppäkangas, Sebastian Zanker, Michael Marthaler, Jan-Michael Reiner

引用次数: 0

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