Pub Date : 2024-06-24DOI: 10.1109/TQE.2024.3418094
André Sequeira;Luis Paulo Santos;Luis Soares Barbosa
This article delves into the role of the quantum Fisher information matrix (FIM) in enhancing the performance of parameterized quantum circuit (PQC)-based reinforcement learning agents. While previous studies have highlighted the effectiveness of PQC-based policies preconditioned with the quantum FIM in contextual bandits, its impact in broader reinforcement learning contexts, such as Markov decision processes, is less clear. Through a detailed analysis of Löwner inequalities between quantum and classical FIMs, this study uncovers the nuanced distinctions and implications of using each type of FIM. Our results indicate that a PQC-based agent using the quantum FIM without additional insights typically incurs a larger approximation error and does not guarantee improved performance compared to the classical FIM. Empirical evaluations in classic control benchmarks suggest even though quantum FIM preconditioning outperforms standard gradient ascent, in general, it is not superior to classical FIM preconditioning.
本文深入探讨了量子费雪信息矩阵（FIM）在提高基于参数化量子电路（PQC）的强化学习代理性能方面的作用。以往的研究强调了基于参数量子电路的策略以量子费雪信息矩阵为前提条件在情境匪帮中的有效性，但其在更广泛的强化学习环境（如马尔可夫决策过程）中的影响却不太明确。通过详细分析量子和经典 FIM 之间的洛纳不等式，本研究揭示了使用每种 FIM 的细微区别和影响。我们的研究结果表明，与经典 FIM 相比，基于 PQC 的代理在使用量子 FIM 时，如果没有额外的洞察力，通常会产生更大的近似误差，并且不能保证性能的提高。经典控制基准中的经验评估表明，尽管量子 FIM 预处理优于标准梯度上升，但总体而言，它并不优于经典 FIM 预处理。
{"title":"On Quantum Natural Policy Gradients","authors":"André Sequeira;Luis Paulo Santos;Luis Soares Barbosa","doi":"10.1109/TQE.2024.3418094","DOIUrl":"https://doi.org/10.1109/TQE.2024.3418094","url":null,"abstract":"This article delves into the role of the quantum Fisher information matrix (FIM) in enhancing the performance of parameterized quantum circuit (PQC)-based reinforcement learning agents. While previous studies have highlighted the effectiveness of PQC-based policies preconditioned with the quantum FIM in contextual bandits, its impact in broader reinforcement learning contexts, such as Markov decision processes, is less clear. Through a detailed analysis of Löwner inequalities between quantum and classical FIMs, this study uncovers the nuanced distinctions and implications of using each type of FIM. Our results indicate that a PQC-based agent using the quantum FIM without additional insights typically incurs a larger approximation error and does not guarantee improved performance compared to the classical FIM. Empirical evaluations in classic control benchmarks suggest even though quantum FIM preconditioning outperforms standard gradient ascent, in general, it is not superior to classical FIM preconditioning.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-11"},"PeriodicalIF":0.0,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10569042","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141964710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sapphire substrates have recently been recognized for their potential to improve the coherence time of superconducting qubits. However, due to challenges in via fabrication, silicon substrates have been predominantly used for qubits. In this study, we fabricated vias on sapphire substrates using lasers and deposited TiN films by chemical vapor deposition. Cross-sectional views of the via confirmed uniform thickness of the TiN film along the via wall. In addition, the TiN film exhibited a superconducting transition at 4.5 K, demonstrating the successful deposition of a high-quality homogeneous superconducting film. This represents the first example of realizing superconducting through-substrate vias on sapphire substrates, a crucial first step toward achieving the 3-D integration of qubits while maintaining coherence time.
蓝宝石衬底最近被认为具有改善超导量子比特相干时间的潜力。然而，由于通孔制作方面的挑战，硅衬底一直是量子比特的主要使用材料。在这项研究中，我们利用激光在蓝宝石基底上制作了通孔，并通过化学气相沉积沉积了 TiN 薄膜。通孔的横截面图证实，TiN 薄膜沿通孔壁的厚度均匀一致。此外，TiN 薄膜在 4.5 K 时出现了超导转变，证明成功沉积了高质量的均匀超导薄膜。这是在蓝宝石衬底上实现超导通孔的首个实例，是实现量子位三维集成并保持相干时间的关键第一步。
{"title":"Superconducting Through-Substrate Vias on Sapphire Substrates for Quantum Circuits","authors":"Kiyotaka Mukasa;Yusuke Nuruki;Hayato Kubo;Yoshihide Narahara;Motohiro Umehara;Kazuyuki Fujie","doi":"10.1109/TQE.2024.3416963","DOIUrl":"https://doi.org/10.1109/TQE.2024.3416963","url":null,"abstract":"Sapphire substrates have recently been recognized for their potential to improve the coherence time of superconducting qubits. However, due to challenges in via fabrication, silicon substrates have been predominantly used for qubits. In this study, we fabricated vias on sapphire substrates using lasers and deposited TiN films by chemical vapor deposition. Cross-sectional views of the via confirmed uniform thickness of the TiN film along the via wall. In addition, the TiN film exhibited a superconducting transition at 4.5 K, demonstrating the successful deposition of a high-quality homogeneous superconducting film. This represents the first example of realizing superconducting through-substrate vias on sapphire substrates, a crucial first step toward achieving the 3-D integration of qubits while maintaining coherence time.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10566011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141602463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-19DOI: 10.1109/TQE.2024.3416836
Luc Enthoven;Masoud Babaie;Fabio Sebastiano
Quantum processors based on color centers in diamond are promising candidates for future large-scale quantum computers thanks to their flexible optical interface, (relatively) high operating temperature, and high-fidelity operation. Similar to other quantum computing platforms, the electrical interface required to control and read out such qubits may limit both the performance of the whole system and its scalability. To address this challenge, this work analyzes the requirements of the electrical interface and investigates how to efficiently implement the electronic controller in a scalable architecture comprising a large number of identical unit cells. Among the different discussed functionalities, a specific focus is devoted to the generation of the static and dynamic magnetic fields driving the electron and nuclear spins, because of their major impact on fidelity and scalability. Following the derived requirements, different system architectures, such as a qubit frequency-multiplexing scheme, are considered to identify the most power efficient approach, especially in the presence of inhomogeneity of the qubit Larmor frequency across the processor. As a result, a non-frequency-multiplexed 1- $,mathrm{m}mathrm{m}^{2}$ unit-cell architecture is proposed as the optimal solution, able to address up to one electron-spin qubit and nine nuclear-spin qubits within a 3-mW average power consumption, thus establishing the baseline for the scalable electrical interface for future large-scale color-center quantum computers.
{"title":"Optimizing the Electrical Interface for Large-Scale Color-Center Quantum Processors","authors":"Luc Enthoven;Masoud Babaie;Fabio Sebastiano","doi":"10.1109/TQE.2024.3416836","DOIUrl":"https://doi.org/10.1109/TQE.2024.3416836","url":null,"abstract":"Quantum processors based on color centers in diamond are promising candidates for future large-scale quantum computers thanks to their flexible optical interface, (relatively) high operating temperature, and high-fidelity operation. Similar to other quantum computing platforms, the electrical interface required to control and read out such qubits may limit both the performance of the whole system and its scalability. To address this challenge, this work analyzes the requirements of the electrical interface and investigates how to efficiently implement the electronic controller in a scalable architecture comprising a large number of identical unit cells. Among the different discussed functionalities, a specific focus is devoted to the generation of the static and dynamic magnetic fields driving the electron and nuclear spins, because of their major impact on fidelity and scalability. Following the derived requirements, different system architectures, such as a qubit frequency-multiplexing scheme, are considered to identify the most power efficient approach, especially in the presence of inhomogeneity of the qubit Larmor frequency across the processor. As a result, a non-frequency-multiplexed 1-\u0000<inline-formula><tex-math>$,mathrm{m}mathrm{m}^{2}$</tex-math></inline-formula>\u0000 unit-cell architecture is proposed as the optimal solution, able to address up to one electron-spin qubit and nine nuclear-spin qubits within a 3-mW average power consumption, thus establishing the baseline for the scalable electrical interface for future large-scale color-center quantum computers.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-17"},"PeriodicalIF":0.0,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10564136","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141602424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The drug design process currently requires considerable time and resources to develop each new compound that enters the market. This work develops an application of hybrid quantum generative models based on the integration of parameterized quantum circuits into known molecular generative adversarial networks and proposes quantum cycle architectures that improve model performance and stability during training. Through extensive experimentation on benchmark drug design datasets, quantum machine 9 (QM9) and PubChemQC 9 (PC9), the introduced models are shown to outperform the previously achieved scores. Most prominently, the new scores indicate an increase of up to 30% in the quantitative estimation of druglikeness. The new hybrid quantum machine learning algorithms, as well as the achieved scores of pharmacokinetic properties, contribute to the development of fast and accurate drug discovery processes.
{"title":"Hybrid Quantum Cycle Generative Adversarial Network for Small Molecule Generation","authors":"Matvei Anoshin;Asel Sagingalieva;Christopher Mansell;Dmitry Zhiganov;Vishal Shete;Markus Pflitsch;Alexey Melnikov","doi":"10.1109/TQE.2024.3414264","DOIUrl":"https://doi.org/10.1109/TQE.2024.3414264","url":null,"abstract":"The drug design process currently requires considerable time and resources to develop each new compound that enters the market. This work develops an application of hybrid quantum generative models based on the integration of parameterized quantum circuits into known molecular generative adversarial networks and proposes quantum cycle architectures that improve model performance and stability during training. Through extensive experimentation on benchmark drug design datasets, quantum machine 9 (QM9) and PubChemQC 9 (PC9), the introduced models are shown to outperform the previously achieved scores. Most prominently, the new scores indicate an increase of up to 30% in the quantitative estimation of druglikeness. The new hybrid quantum machine learning algorithms, as well as the achieved scores of pharmacokinetic properties, contribute to the development of fast and accurate drug discovery processes.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-14"},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10556803","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141630961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-11DOI: 10.1109/TQE.2024.3412165
Ioannis Krikidis
In this article, we study the problem of digital pre/postcoding design in multiple-input multiple-output (MIMO) systems with 1-b resolution per complex dimension. The optimal solution that maximizes the received signal-to-noise ratio relies on an NP-hard combinatorial problem that requires exhaustive searching with exponential complexity. By using the principles of alternating optimization and quantum annealing (QA), an iterative QA-based algorithm is proposed that achieves near-optimal performance with polynomial complexity. The algorithm is associated with a rigorous mathematical framework that casts the pre/postcoding vector design to appropriate real-valued quadratic unconstrained binary optimization (QUBO) problems. Experimental results in a state-of-the-art D-WAVE QA device validate the efficiency of the proposed algorithm. To further improve the efficiency of the D-WAVE quantum device, a new preprocessing technique, which preserves the quadratic QUBO matrix from the detrimental effects of the Hamiltonian noise through nonlinear companding, is proposed. The proposed preprocessing technique significantly improves the quality of the D-WAVE solutions as well as the occurrence probability of the optimal solution.
{"title":"MIMO With 1-b Pre/Postcoding Resolution: A Quantum Annealing Approach","authors":"Ioannis Krikidis","doi":"10.1109/TQE.2024.3412165","DOIUrl":"10.1109/TQE.2024.3412165","url":null,"abstract":"In this article, we study the problem of digital pre/postcoding design in multiple-input multiple-output (MIMO) systems with 1-b resolution per complex dimension. The optimal solution that maximizes the received signal-to-noise ratio relies on an NP-hard combinatorial problem that requires exhaustive searching with exponential complexity. By using the principles of alternating optimization and quantum annealing (QA), an iterative QA-based algorithm is proposed that achieves near-optimal performance with polynomial complexity. The algorithm is associated with a rigorous mathematical framework that casts the pre/postcoding vector design to appropriate real-valued quadratic unconstrained binary optimization (QUBO) problems. Experimental results in a state-of-the-art D-WAVE QA device validate the efficiency of the proposed algorithm. To further improve the efficiency of the D-WAVE quantum device, a new preprocessing technique, which preserves the quadratic QUBO matrix from the detrimental effects of the Hamiltonian noise through nonlinear companding, is proposed. The proposed preprocessing technique significantly improves the quality of the D-WAVE solutions as well as the occurrence probability of the optimal solution.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10553303","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141373041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As scaling becomes a key issue for large-scale quantum computing, hardware control systems will become increasingly costly in resources. This article presents a compact direct digital synthesis architecture for signal generation adapted for spin qubits that is scalable in terms of waveform accuracy and the number of synchronized channels. The architecture can produce programmable combinations of ramps, frequency combs, and arbitrary waveform generation (AWG) at 5 GS/s, with a worst-case digital feedback latency of 76.8 ns. The field-programmable gate array (FPGA)-based system is highly configurable and takes advantage of bitstream switching to achieve the high flexibility required for scalable calibration. The architecture also provides GHz rate, multiplexed, in-phase and quadrature component, single-side band modulation for scalable reflectometry. This architecture has been validated in hardware on a Xilinx ZCU111 FPGA demonstrating the mixing of complex signals and the quality of the frequency comb generation for multiplexed control and measurement. The key benefits of this design are the increase of controllability of ramps at the digital-to-analog converter (DAC) frequency and the reduction in memory requirements by several orders of magnitude compared with existing AWG-based architectures. The hardware for a single channel is very compact, 2% of ZCU111 logic resources for one DAC lane in the default configuration, leaving significant circuit resources for integrated feedback, calibration, and quantum error correction.
{"title":"FASQuiC: Flexible Architecture for Scalable Spin Qubit Control","authors":"Mathieu Toubeix;Eric Guthmuller;Adrian Evans;Antoine Faurie;Tristan Meunier","doi":"10.1109/TQE.2024.3409811","DOIUrl":"https://doi.org/10.1109/TQE.2024.3409811","url":null,"abstract":"As scaling becomes a key issue for large-scale quantum computing, hardware control systems will become increasingly costly in resources. This article presents a compact direct digital synthesis architecture for signal generation adapted for spin qubits that is scalable in terms of waveform accuracy and the number of synchronized channels. The architecture can produce programmable combinations of ramps, frequency combs, and arbitrary waveform generation (AWG) at 5 GS/s, with a worst-case digital feedback latency of 76.8 ns. The field-programmable gate array (FPGA)-based system is highly configurable and takes advantage of bitstream switching to achieve the high flexibility required for scalable calibration. The architecture also provides GHz rate, multiplexed, in-phase and quadrature component, single-side band modulation for scalable reflectometry. This architecture has been validated in hardware on a Xilinx ZCU111 FPGA demonstrating the mixing of complex signals and the quality of the frequency comb generation for multiplexed control and measurement. The key benefits of this design are the increase of controllability of ramps at the digital-to-analog converter (DAC) frequency and the reduction in memory requirements by several orders of magnitude compared with existing AWG-based architectures. The hardware for a single channel is very compact, 2% of ZCU111 logic resources for one DAC lane in the default configuration, leaving significant circuit resources for integrated feedback, calibration, and quantum error correction.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-16"},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10549805","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141453369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-04DOI: 10.1109/TQE.2024.3409309
Zichang He;Bo Peng;Yuri Alexeev;Zheng Zhang
Given their potential to demonstrate near-term quantum advantage, variational quantum algorithms (VQAs) have been extensively studied. Although numerous techniques have been developed for VQA parameter optimization, it remains a significant challenge. A practical issue is that quantum noise is highly unstable and thus it is likely to shift in real time. This presents a critical problem as an optimized VQA ansatz may not perform effectively under a different noise environment. For the first time, we explore how to optimize VQA parameters to be robust against unknown shifted noise. We model the noise level as a random variable with an unknown probability density function (PDF), and we assume that the PDF may shift within an uncertainty set. This assumption guides us to formulate a distributionally robust optimization problem, with the goal of finding parameters that maintain effectiveness under shifted noise. We utilize a distributionally robust Bayesian optimization solver for our proposed formulation. This provides numerical evidence in both the quantum approximate optimization algorithm and the variational quantum eigensolver with hardware-efficient ansatz, indicating that we can identify parameters that perform more robustly under shifted noise. We regard this work as the first step toward improving the reliability of VQAs influenced by shifted noise from the parameter optimization perspective.
{"title":"Distributionally Robust Variational Quantum Algorithms With Shifted Noise","authors":"Zichang He;Bo Peng;Yuri Alexeev;Zheng Zhang","doi":"10.1109/TQE.2024.3409309","DOIUrl":"https://doi.org/10.1109/TQE.2024.3409309","url":null,"abstract":"Given their potential to demonstrate near-term quantum advantage, variational quantum algorithms (VQAs) have been extensively studied. Although numerous techniques have been developed for VQA parameter optimization, it remains a significant challenge. A practical issue is that quantum noise is highly unstable and thus it is likely to shift in real time. This presents a critical problem as an optimized VQA ansatz may not perform effectively under a different noise environment. For the first time, we explore how to optimize VQA parameters to be robust against unknown shifted noise. We model the noise level as a random variable with an unknown probability density function (PDF), and we assume that the PDF may shift within an uncertainty set. This assumption guides us to formulate a distributionally robust optimization problem, with the goal of finding parameters that maintain effectiveness under shifted noise. We utilize a distributionally robust Bayesian optimization solver for our proposed formulation. This provides numerical evidence in both the quantum approximate optimization algorithm and the variational quantum eigensolver with hardware-efficient ansatz, indicating that we can identify parameters that perform more robustly under shifted noise. We regard this work as the first step toward improving the reliability of VQAs influenced by shifted noise from the parameter optimization perspective.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-12"},"PeriodicalIF":0.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10547365","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141430031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-03DOI: 10.1109/TQE.2024.3408757
Weining Dai;Kevin A. Brown;Thomas G. Robertazzi
Trapped ions (TIs) are at the forefront of quantum computing implementation, offering unparalleled coherence, fidelity, and connectivity. However, the scalability of TI systems is hampered by the limited capacity of individual ion traps, necessitating intricate ion shuttling for advanced computational tasks. The quantum charge-coupled device (QCCD) framework has emerged as a promising solution, facilitating ion mobility for universal quantum computation. Current QCCD architectures predominantly feature a linear topology, which is increasingly recognized as inefficient for complex quantum operations. Anticipating the shift toward more efficacious designs, this article introduces an innovative quantum scheduling strategy optimized for parallel QCCD topologies. Our strategy proposes a probabilistic formula for ion movement, alongside ingenious methods for local layer generation and layer compression, yielding a significant reduction in ion shuttle times. Through simulations, we demonstrate that our strategy not only substantially outstrips the linear model but also exhibits better performance over other parallel strategies that employ greedy algorithms. This is achieved through our nuanced resolution of complexities, such as traffic blocks and trap capacity limitations. The consequent reduction in shuttle operations leads to lower energy consumption and an enhancement in the quantum computer's fidelity, ultimately accelerating program execution times.
{"title":"Advanced Shuttle Strategies for Parallel QCCD Architectures","authors":"Weining Dai;Kevin A. Brown;Thomas G. Robertazzi","doi":"10.1109/TQE.2024.3408757","DOIUrl":"https://doi.org/10.1109/TQE.2024.3408757","url":null,"abstract":"Trapped ions (TIs) are at the forefront of quantum computing implementation, offering unparalleled coherence, fidelity, and connectivity. However, the scalability of TI systems is hampered by the limited capacity of individual ion traps, necessitating intricate ion shuttling for advanced computational tasks. The quantum charge-coupled device (QCCD) framework has emerged as a promising solution, facilitating ion mobility for universal quantum computation. Current QCCD architectures predominantly feature a linear topology, which is increasingly recognized as inefficient for complex quantum operations. Anticipating the shift toward more efficacious designs, this article introduces an innovative quantum scheduling strategy optimized for parallel QCCD topologies. Our strategy proposes a probabilistic formula for ion movement, alongside ingenious methods for local layer generation and layer compression, yielding a significant reduction in ion shuttle times. Through simulations, we demonstrate that our strategy not only substantially outstrips the linear model but also exhibits better performance over other parallel strategies that employ greedy algorithms. This is achieved through our nuanced resolution of complexities, such as traffic blocks and trap capacity limitations. The consequent reduction in shuttle operations leads to lower energy consumption and an enhancement in the quantum computer's fidelity, ultimately accelerating program execution times.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-18"},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10546265","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141474918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Grover adaptive search (GAS) is a quantum exhaustive search algorithm designed to solve binary optimization problems. In this article, we propose higher order binary formulations that can simultaneously reduce the numbers of qubits and gates required for GAS. Specifically, we consider two novel strategies: one that reduces the number of gates through polynomial factorization, and the other that halves the order of the objective function, subsequently decreasing circuit runtime and implementation cost. Our analysis demonstrates that the proposed higher order formulations improve the convergence performance of GAS by reducing both the search space size and the number of quantum gates. Our strategies are also beneficial for general combinatorial optimization problems using one-hot encoding.
格罗弗自适应搜索（GAS）是一种量子穷举搜索算法，旨在解决二进制优化问题。在本文中，我们提出了能同时减少 GAS 所需的量子比特和门数量的高阶二进制公式。具体来说，我们考虑了两种新策略：一种是通过多项式因式分解减少门的数量，另一种是将目标函数的阶数减半，从而减少电路运行时间和实现成本。我们的分析表明，通过减少搜索空间大小和量子门数量，所提出的高阶公式改善了 GAS 的收敛性能。我们的策略也适用于使用单次编码的一般组合优化问题。
{"title":"Accelerating Grover Adaptive Search: Qubit and Gate Count Reduction Strategies With Higher Order Formulations","authors":"Yuki Sano;Kosuke Mitarai;Naoki Yamamoto;Naoki Ishikawa","doi":"10.1109/TQE.2024.3393437","DOIUrl":"https://doi.org/10.1109/TQE.2024.3393437","url":null,"abstract":"Grover adaptive search (GAS) is a quantum exhaustive search algorithm designed to solve binary optimization problems. In this article, we propose higher order binary formulations that can simultaneously reduce the numbers of qubits and gates required for GAS. Specifically, we consider two novel strategies: one that reduces the number of gates through polynomial factorization, and the other that halves the order of the objective function, subsequently decreasing circuit runtime and implementation cost. Our analysis demonstrates that the proposed higher order formulations improve the convergence performance of GAS by reducing both the search space size and the number of quantum gates. Our strategies are also beneficial for general combinatorial optimization problems using one-hot encoding.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-12"},"PeriodicalIF":0.0,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10508492","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141068947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-25DOI: 10.1109/TQE.2024.3393416
Leonardo Oleynik;Junaid Ur Rehman;Hayder Al-Hraishawi;Symeon Chatzinotas
This article explores the performance of quantum communication systems in the presence of noise and focuses on finding the optimal encoding for maximizing the classical communication rate, approaching the classical capacity in some scenarios. Instead of theoretically bounding the ultimate capacity of the channel, we adopt a signal processing perspective to estimate the achievable performance of a physically available but otherwise unknown quantum channel. By employing a variational algorithm to estimate the trace distance between quantum states, we numerically determine the optimal encoding protocol for the amplitude damping and Pauli channels. Our simulations demonstrate the convergence and accuracy of the method with a few iterations, confirming that optimal conditions for binary quantum communication systems can be variationally determined with minimal computation. Furthermore, since the channel knowledge is not required at the transmitter or at the receiver, these results can be employed in arbitrary quantum communication systems, including satellite-based communication systems, a particularly relevant platform for the quantum Internet.
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