Pub Date : 2024-04-23DOI: 10.1109/TQE.2024.3392834
David Winderl;Nicola Franco;Jeanette Miriam Lorenz
Variational quantum optimization algorithms, such as the variational quantum eigensolver (VQE) or the quantum approximate optimization algorithm (QAOA), are among the most studied quantum algorithms. In our work, we evaluate and improve an algorithm based on the VQE, which uses exponentially fewer qubits compared to the QAOA. We highlight the numerical instabilities generated by encoding the problem into the variational ansatz and propose a classical optimization procedure to find the ground state of the ansatz in fewer iterations with a better or similar objective. In addition, we propose a method to embed the linear interpolation of the MaxCut problem on a quantum device. Furthermore, we compare classical optimizers for this variational ansatz on quadratic unconstrained binary optimization and graph partitioning problems.
{"title":"A Comparative Study on Solving Optimization Problems With Exponentially Fewer Qubits","authors":"David Winderl;Nicola Franco;Jeanette Miriam Lorenz","doi":"10.1109/TQE.2024.3392834","DOIUrl":"https://doi.org/10.1109/TQE.2024.3392834","url":null,"abstract":"Variational quantum optimization algorithms, such as the variational quantum eigensolver (VQE) or the quantum approximate optimization algorithm (QAOA), are among the most studied quantum algorithms. In our work, we evaluate and improve an algorithm based on the VQE, which uses exponentially fewer qubits compared to the QAOA. We highlight the numerical instabilities generated by encoding the problem into the variational ansatz and propose a classical optimization procedure to find the ground state of the ansatz in fewer iterations with a better or similar objective. In addition, we propose a method to embed the linear interpolation of the MaxCut problem on a quantum device. Furthermore, we compare classical optimizers for this variational ansatz on quadratic unconstrained binary optimization and graph partitioning problems.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10506971","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140902538","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}
Quantum information cannot be perfectly cloned, but approximate copies of quantum information can be generated. Quantum telecloning combines approximate quantum cloning, more typically referred to as quantum cloning, and quantum teleportation. Quantum telecloning allows approximate copies of quantum information to be constructed by separate parties, using the classical results of a Bell measurement made on a prepared quantum telecloning state. Quantum telecloning can be implemented as a circuit on quantum computers using a classical coprocessor to compute classical feedforward instructions using if statements based on the results of a midcircuit Bell measurement in real time. We present universal symmetric optimal $1 rightarrow M$ telecloning circuits and experimentally demonstrate these quantum telecloning circuits for $M=2$ up to $M=10$ , natively executed with real-time classical control systems on IBM Quantum superconducting processors, known as dynamic circuits. We perform the cloning procedure on many different message states across the Bloch sphere, on seven IBM Quantum processors, optionally using the error suppression technique X–X sequence digital dynamical decoupling. Two circuit optimizations are utilized: one that removes ancilla qubits for $M=2, 3$ , and one that reduces the total number of gates in the circuit but still uses ancilla qubits. Parallel single-qubit tomography with maximum likelihood estimation density matrix reconstruction is used in order to compute the mixed-state density matrices of the clone qubits, and clone quality is measured using quantum fidelity. These results present one of the largest and most comprehensive noisy intermediate-scale quantum computer experimental analyses on (single qubit) quantum telecloning to date. The clone fidelity sharply decreases to 0.5 for $M > 5$ , but for $M=2$ , we are able to achieve a mean clone fidelity of up to 0.79 using dynamical decoupling.
量子信息无法完美克隆，但可以生成量子信息的近似副本。量子远程克隆结合了近似量子克隆（通常称为量子克隆）和量子远程传输。量子远距克隆可以利用对准备好的量子远距克隆状态进行贝尔测量的经典结果，由不同的当事人构建量子信息的近似副本。量子远程克隆可以在量子计算机上以电路的形式实现，使用经典协处理器，根据电路中段贝尔测量的结果，使用 if 语句实时计算经典前馈指令。我们提出了通用对称最优1美元/rightarrow M美元远程克隆电路，并在实验中演示了这些M=2美元到M=10美元的量子远程克隆电路，在IBM量子超导处理器（称为动态电路）上使用实时经典控制系统原生执行。我们在七台 IBM 量子处理器上对布洛赫球上的许多不同信息状态执行克隆程序，可选择使用误差抑制技术 X-X 序列数字动态解耦。我们采用了两种电路优化方法：一种是在 $M=2、3$ 时移除辅助量子比特，另一种是减少电路中的门总数，但仍使用辅助量子比特。为了计算克隆量子比特的混合态密度矩阵，我们使用了并行单量子比特层析技术和最大似然估计密度矩阵重构技术，并使用量子保真度来测量克隆质量。这些结果展示了迄今为止对（单量子比特）量子远程克隆进行的最大规模、最全面的噪声中型量子计算机实验分析之一。对于 $M > 5$，克隆保真度急剧下降至 0.5，但对于 $M=2$，我们能够利用动态解耦实现高达 0.79 的平均克隆保真度。
{"title":"Probing Quantum Telecloning on Superconducting Quantum Processors","authors":"Elijah Pelofske;Andreas Bärtschi;Stephan Eidenbenz;Bryan Garcia;Boris Kiefer","doi":"10.1109/TQE.2024.3391654","DOIUrl":"https://doi.org/10.1109/TQE.2024.3391654","url":null,"abstract":"Quantum information cannot be perfectly cloned, but approximate copies of quantum information can be generated. Quantum telecloning combines approximate quantum cloning, more typically referred to as quantum cloning, and quantum teleportation. Quantum telecloning allows approximate copies of quantum information to be constructed by separate parties, using the classical results of a Bell measurement made on a prepared quantum telecloning state. Quantum telecloning can be implemented as a circuit on quantum computers using a classical coprocessor to compute classical feedforward instructions using if statements based on the results of a midcircuit Bell measurement in real time. We present universal symmetric optimal \u0000<inline-formula><tex-math>$1 rightarrow M$</tex-math></inline-formula>\u0000 telecloning circuits and experimentally demonstrate these quantum telecloning circuits for \u0000<inline-formula><tex-math>$M=2$</tex-math></inline-formula>\u0000 up to \u0000<inline-formula><tex-math>$M=10$</tex-math></inline-formula>\u0000, natively executed with real-time classical control systems on IBM Quantum superconducting processors, known as dynamic circuits. We perform the cloning procedure on many different message states across the Bloch sphere, on seven IBM Quantum processors, optionally using the error suppression technique X–X sequence digital dynamical decoupling. Two circuit optimizations are utilized: one that removes ancilla qubits for \u0000<inline-formula><tex-math>$M=2, 3$</tex-math></inline-formula>\u0000, and one that reduces the total number of gates in the circuit but still uses ancilla qubits. Parallel single-qubit tomography with maximum likelihood estimation density matrix reconstruction is used in order to compute the mixed-state density matrices of the clone qubits, and clone quality is measured using quantum fidelity. These results present one of the largest and most comprehensive noisy intermediate-scale quantum computer experimental analyses on (single qubit) quantum telecloning to date. The clone fidelity sharply decreases to 0.5 for \u0000<inline-formula><tex-math>$M > 5$</tex-math></inline-formula>\u0000, but for \u0000<inline-formula><tex-math>$M=2$</tex-math></inline-formula>\u0000, we are able to achieve a mean clone fidelity of up to 0.79 using dynamical decoupling.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-19"},"PeriodicalIF":0.0,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10505824","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140948912","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 : 2024-04-16DOI: 10.1109/TQE.2024.3386753
Shao-Hen Chiew;Kilian Poirier;Rajesh Mishra;Ulrike Bornheimer;Ewan Munro;Si Han Foon;Christopher Wanru Chen;Wei Sheng Lim;Chee Wei Nga
Multiobjective optimization is a ubiquitous problem that arises naturally in many scientific and industrial areas. Network routing optimization with multiobjective performance demands falls into this problem class, and finding good quality solutions at large scales is generally challenging. In this work, we develop a scheme with which near-term quantum computers can be applied to solve multiobjective combinatorial optimization problems. We study the application of this scheme to the network routing problem in detail, by first mapping it to the multiobjective shortest-path problem. Focusing on an implementation based on the quantum approximate optimization algorithm (QAOA)—the go-to approach for tackling optimization problems on near-term quantum computers—we examine the Pareto plot that results from the scheme and qualitatively analyze its ability to produce Pareto-optimal solutions. We further provide theoretical and numerical scaling analyses of the resource requirements and performance of QAOA and identify key challenges associated with this approach. Finally, through Amazon Braket, we execute small-scale implementations of our scheme on the IonQ Harmony 11-qubit quantum computer.
{"title":"Multiobjective Optimization and Network Routing With Near-Term Quantum Computers","authors":"Shao-Hen Chiew;Kilian Poirier;Rajesh Mishra;Ulrike Bornheimer;Ewan Munro;Si Han Foon;Christopher Wanru Chen;Wei Sheng Lim;Chee Wei Nga","doi":"10.1109/TQE.2024.3386753","DOIUrl":"https://doi.org/10.1109/TQE.2024.3386753","url":null,"abstract":"Multiobjective optimization is a ubiquitous problem that arises naturally in many scientific and industrial areas. Network routing optimization with multiobjective performance demands falls into this problem class, and finding good quality solutions at large scales is generally challenging. In this work, we develop a scheme with which near-term quantum computers can be applied to solve multiobjective combinatorial optimization problems. We study the application of this scheme to the network routing problem in detail, by first mapping it to the multiobjective shortest-path problem. Focusing on an implementation based on the quantum approximate optimization algorithm (QAOA)—the go-to approach for tackling optimization problems on near-term quantum computers—we examine the Pareto plot that results from the scheme and qualitatively analyze its ability to produce Pareto-optimal solutions. We further provide theoretical and numerical scaling analyses of the resource requirements and performance of QAOA and identify key challenges associated with this approach. Finally, through Amazon Braket, we execute small-scale implementations of our scheme on the IonQ Harmony 11-qubit quantum computer.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-19"},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10502334","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140844432","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 : 2024-04-05DOI: 10.1109/TQE.2024.3385673
Bagas Prabowo;Jurgen Dijkema;Xiao Xue;Fabio Sebastiano;Lieven M. K. Vandersypen;Masoud Babaie
In semiconductor spin quantum bits (qubits), the radio-frequency (RF) gate-based readout is a promising solution for future large-scale integration, as it allows for a fast, frequency-multiplexed readout architecture, enabling multiple qubits to be read out simultaneously. This article introduces a theoretical framework to evaluate the effect of various parameters, such as the readout probe power, readout chain's noise performance, and integration time on the intrinsic readout signal-to-noise ratio, and thus readout fidelity of RF gate-based readout systems. By analyzing the underlying physics of spin qubits during readout, this work proposes a qubit readout model that takes into account the qubit's quantum mechanical properties, providing a way to evaluate the tradeoffs among the aforementioned parameters. The validity of the proposed model is evaluated by comparing the simulation and experimental results. The proposed analytical approach, the developed model, and the experimental results enable designers to optimize the entire readout chain effectively, thus leading to a faster, lower power readout system with integrated cryogenic electronics.
{"title":"Modeling and Experimental Validation of the Intrinsic SNR in Spin Qubit Gate-Based Readout and Its Impacts on Readout Electronics","authors":"Bagas Prabowo;Jurgen Dijkema;Xiao Xue;Fabio Sebastiano;Lieven M. K. Vandersypen;Masoud Babaie","doi":"10.1109/TQE.2024.3385673","DOIUrl":"https://doi.org/10.1109/TQE.2024.3385673","url":null,"abstract":"In semiconductor spin quantum bits (qubits), the radio-frequency (RF) gate-based readout is a promising solution for future large-scale integration, as it allows for a fast, frequency-multiplexed readout architecture, enabling multiple qubits to be read out simultaneously. This article introduces a theoretical framework to evaluate the effect of various parameters, such as the readout probe power, readout chain's noise performance, and integration time on the intrinsic readout signal-to-noise ratio, and thus readout fidelity of RF gate-based readout systems. By analyzing the underlying physics of spin qubits during readout, this work proposes a qubit readout model that takes into account the qubit's quantum mechanical properties, providing a way to evaluate the tradeoffs among the aforementioned parameters. The validity of the proposed model is evaluated by comparing the simulation and experimental results. The proposed analytical approach, the developed model, and the experimental results enable designers to optimize the entire readout chain effectively, thus leading to a faster, lower power readout system with integrated cryogenic electronics.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-15"},"PeriodicalIF":0.0,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10493854","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140844433","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 : 2024-04-04DOI: 10.1109/TQE.2024.3385372
Gayathree M. Vinod;Anil Shaji
We implement a simulation of a quantum field theory in 1+1 space–time dimensions on a gate-based quantum computer using the light-front formulation of the theory. The nonperturbative simulation of the Yukawa model field theory is verified on IBM's simulator and is also demonstrated on a small-scale IBM circuit-based quantum processor, on the cloud, using IBM Qiskit. The light-front formulation allows for controlling the resource requirement and complexity of the computation with commensurate tradeoffs in accuracy and detail by modulating a single parameter, namely, the harmonic resolution. Qubit operators for the Bosonic excitations were also created and were used along with the Fermionic ones already available, to simulate the theory involving all of these particles. With the restriction on the number of logical qubits available on the existent gate-based noisy intermediate-scale quantum (NISQ) devices, the Trotterization approximation is also used. We show that experimentally relevant quantities, such as cross sections for various processes and survival probabilities of various states, can be computed. We also explore the inaccuracies introduced by the bounds on achievable harmonic resolution and Trotter steps placed by the limited number of qubits and circuit depth supported by present-day NISQ devices.
我们在基于门的量子计算机上，利用量子场论的光前表述，实现了 1+1 时空维度的量子场论模拟。我们在 IBM 的模拟器上验证了汤川模型场论的非微扰模拟，并利用 IBM Qiskit 在云端的小型 IBM 电路量子处理器上进行了演示。光前公式允许通过调节单个参数（即谐波分辨率）来控制计算的资源需求和复杂性，并在精度和细节方面做出相应的权衡。我们还创建了波色子激发的 Qubit 算子，并与已有的费米子算子一起用于模拟涉及所有这些粒子的理论。由于现有的基于门的噪声中量子（NISQ）器件的逻辑量子比特数量有限，因此还使用了特罗特化近似。我们的研究表明，各种过程的截面和各种状态的存活概率等实验相关量都可以计算出来。我们还探讨了由于当今 NISQ 器件支持的量子比特数量和电路深度有限，对可实现谐波分辨率和特罗特阶数的限制所带来的不准确性。
{"title":"Simulating Quantum Field Theories on Gate-Based Quantum Computers","authors":"Gayathree M. Vinod;Anil Shaji","doi":"10.1109/TQE.2024.3385372","DOIUrl":"https://doi.org/10.1109/TQE.2024.3385372","url":null,"abstract":"We implement a simulation of a quantum field theory in 1+1 space–time dimensions on a gate-based quantum computer using the light-front formulation of the theory. The nonperturbative simulation of the Yukawa model field theory is verified on IBM's simulator and is also demonstrated on a small-scale IBM circuit-based quantum processor, on the cloud, using IBM Qiskit. The light-front formulation allows for controlling the resource requirement and complexity of the computation with commensurate tradeoffs in accuracy and detail by modulating a single parameter, namely, the harmonic resolution. Qubit operators for the Bosonic excitations were also created and were used along with the Fermionic ones already available, to simulate the theory involving all of these particles. With the restriction on the number of logical qubits available on the existent gate-based noisy intermediate-scale quantum (NISQ) devices, the Trotterization approximation is also used. We show that experimentally relevant quantities, such as cross sections for various processes and survival probabilities of various states, can be computed. We also explore the inaccuracies introduced by the bounds on achievable harmonic resolution and Trotter steps placed by the limited number of qubits and circuit depth supported by present-day NISQ devices.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-14"},"PeriodicalIF":0.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10491310","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140902539","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 : 2024-03-30DOI: 10.1109/TQE.2024.3407236
David Bucher;Jonas Nüßlein;Corey O'Meara;Ivan Angelov;Benedikt Wimmer;Kumar Ghosh;Giorgio Cortiana;Claudia Linnhoff-Popien
Demand-side response (DSR) is a strategy that enables consumers to actively participate in managing electricity demand. It aims to alleviate strain on the grid during high demand and promote a more balanced and efficient use of (renewable) electricity resources. We implement DSR through discount scheduling, which involves offering discrete price incentives to consumers to adjust their electricity consumption patterns to times when their local energy mix consists of more renewable energy. Since we tailor the discounts to individual customers' consumption, the discount scheduling problem (DSP) becomes a large combinatorial optimization task. Consequently, we adopt a hybrid quantum computing approach, using D-Wave's Leap Hybrid Cloud. We benchmark Leap against Gurobi, a classical mixed-integer optimizer, in terms of solution quality at fixed runtime and fairness in terms of discount allocation. Furthermore, we propose a large-scale decomposition algorithm/heuristic for the DSP, applied with either quantum or classical computers running the subroutines, which significantly reduces the problem size while maintaining solution quality. Using synthetic data generated from real-world data, we observe that the classical decomposition method obtains the best overall solution quality for problem sizes up to 3200 consumers; however, the hybrid quantum approach provides more evenly distributed discounts across consumers.
{"title":"Incentivizing Demand-Side Response Through Discount Scheduling Using Hybrid Quantum Optimization","authors":"David Bucher;Jonas Nüßlein;Corey O'Meara;Ivan Angelov;Benedikt Wimmer;Kumar Ghosh;Giorgio Cortiana;Claudia Linnhoff-Popien","doi":"10.1109/TQE.2024.3407236","DOIUrl":"https://doi.org/10.1109/TQE.2024.3407236","url":null,"abstract":"Demand-side response (DSR) is a strategy that enables consumers to actively participate in managing electricity demand. It aims to alleviate strain on the grid during high demand and promote a more balanced and efficient use of (renewable) electricity resources. We implement DSR through discount scheduling, which involves offering discrete price incentives to consumers to adjust their electricity consumption patterns to times when their local energy mix consists of more renewable energy. Since we tailor the discounts to individual customers' consumption, the discount scheduling problem (DSP) becomes a large combinatorial optimization task. Consequently, we adopt a hybrid quantum computing approach, using D-Wave's Leap Hybrid Cloud. We benchmark Leap against Gurobi, a classical mixed-integer optimizer, in terms of solution quality at fixed runtime and fairness in terms of discount allocation. Furthermore, we propose a large-scale decomposition algorithm/heuristic for the DSP, applied with either quantum or classical computers running the subroutines, which significantly reduces the problem size while maintaining solution quality. Using synthetic data generated from real-world data, we observe that the classical decomposition method obtains the best overall solution quality for problem sizes up to 3200 consumers; however, the hybrid quantum approach provides more evenly distributed discounts across consumers.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-15"},"PeriodicalIF":0.0,"publicationDate":"2024-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10542394","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141435333","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 : 2024-03-29DOI: 10.1109/TQE.2024.3383050
Xia Liu;Geng Liu;Hao-Kai Zhang;Jiaxin Huang;Xin Wang
Variational quantum algorithms (VQAs) are expected to establish valuable applications on near-term quantum computers. However, recent works have pointed out that the performance of VQAs greatly relies on the expressibility of the ansatzes and is seriously limited by optimization issues, such as barren plateaus (i.e., vanishing gradients). This article proposes the state-efficient ansatz (SEA) for accurate ground state preparation with improved trainability. We show that the SEA can generate an arbitrary pure state with much fewer parameters than a universal ansatz, making it efficient for tasks like ground state estimation. Then, we prove that barren plateaus can be efficiently mitigated by the SEA and the trainability can be further improved most quadratically by flexibly adjusting the entangling capability of the SEA. Finally, we investigate a plethora of examples in ground state estimation where we obtain significant improvements in the magnitude of the cost gradient and the convergence speed.
{"title":"Mitigating Barren Plateaus of Variational Quantum Eigensolvers","authors":"Xia Liu;Geng Liu;Hao-Kai Zhang;Jiaxin Huang;Xin Wang","doi":"10.1109/TQE.2024.3383050","DOIUrl":"https://doi.org/10.1109/TQE.2024.3383050","url":null,"abstract":"Variational quantum algorithms (VQAs) are expected to establish valuable applications on near-term quantum computers. However, recent works have pointed out that the performance of VQAs greatly relies on the expressibility of the ansatzes and is seriously limited by optimization issues, such as barren plateaus (i.e., vanishing gradients). This article proposes the state-efficient ansatz (SEA) for accurate ground state preparation with improved trainability. We show that the SEA can generate an arbitrary pure state with much fewer parameters than a universal ansatz, making it efficient for tasks like ground state estimation. Then, we prove that barren plateaus can be efficiently mitigated by the SEA and the trainability can be further improved most quadratically by flexibly adjusting the entangling capability of the SEA. Finally, we investigate a plethora of examples in ground state estimation where we obtain significant improvements in the magnitude of the cost gradient and the convergence speed.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-19"},"PeriodicalIF":0.0,"publicationDate":"2024-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10485449","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142713820","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 : 2024-03-23DOI: 10.1109/TQE.2024.3404502
Jordan Hines;Timothy Proctor
Quantum processors are now able to run quantum circuits that are infeasible to simulate classically, creating a need for benchmarks that assess a quantum processor's rate of errors when running these circuits. Here, we introduce a general technique for creating efficient benchmarks from any set of quantum computations, specified by unitary circuits. Our benchmarks assess the integrated performance of a quantum processor's classical compilation algorithms and its low-level quantum operations. Unlike existing “full-stack benchmarks,” our benchmarks do not require classical simulations of quantum circuits, and they use only efficient classical computations. We use our method to create random circuit benchmarks, including a computationally efficient version of the quantum volume benchmark, and an algorithm-based benchmark that uses Hamiltonian simulation circuits. We perform these benchmarks on IBM Q devices and in simulations, and we compare their results to the results of the existing benchmarking methods.
量子处理器现在能够运行经典模拟不可行的量子电路，因此需要能评估量子处理器运行这些电路时出错率的基准。在这里，我们介绍了一种通用技术，用于从由单元电路指定的任何量子计算集合中创建高效基准。我们的基准可评估量子处理器的经典编译算法及其低级量子操作的综合性能。与现有的 "全栈基准 "不同，我们的基准不需要对量子电路进行经典模拟，而且只使用高效的经典计算。我们使用我们的方法创建随机电路基准，包括量子体积基准的高效计算版本，以及使用哈密尔顿模拟电路的基于算法的基准。我们在 IBM Q 设备和模拟中执行了这些基准，并将其结果与现有基准测试方法的结果进行了比较。
{"title":"Scalable Full-Stack Benchmarks for Quantum Computers","authors":"Jordan Hines;Timothy Proctor","doi":"10.1109/TQE.2024.3404502","DOIUrl":"https://doi.org/10.1109/TQE.2024.3404502","url":null,"abstract":"Quantum processors are now able to run quantum circuits that are infeasible to simulate classically, creating a need for benchmarks that assess a quantum processor's rate of errors when running these circuits. Here, we introduce a general technique for creating efficient benchmarks from any set of quantum computations, specified by unitary circuits. Our benchmarks assess the integrated performance of a quantum processor's classical compilation algorithms and its low-level quantum operations. Unlike existing “full-stack benchmarks,” our benchmarks do not require classical simulations of quantum circuits, and they use only efficient classical computations. We use our method to create random circuit benchmarks, including a computationally efficient version of the quantum volume benchmark, and an algorithm-based benchmark that uses Hamiltonian simulation circuits. We perform these benchmarks on IBM Q devices and in simulations, and we compare their results to the results of the existing benchmarking methods.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-12"},"PeriodicalIF":0.0,"publicationDate":"2024-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10538040","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142169681","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 : 2024-03-16DOI: 10.1109/TQE.2024.3401857
Eric Sabo;Arun B. Aloshious;Kenneth R. Brown
Trellis decoders are a general decoding technique first applied to qubit-based quantum error correction codes by Ollivier and Tillich in 2006. Here, we improve the scalability and practicality of their theory, show that it has strong structure, extend the results using classical coding theory as a guide, and demonstrate a canonical form from which the structural properties of the decoding graph may be computed. The resulting formalism is valid for any prime-dimensional quantum system. The modified decoder works for any stabilizer code $S$ and separates into two parts: 1) a one-time offline computation that builds a compact graphical representation of the normalizer of the code, $mathcal {S}^{perp}$ and 2) a quick, parallel, online query of the resulting vertices using the Viterbi algorithm. We show the utility of trellis decoding by applying it to four high-density length-20 stabilizer codes for depolarizing noise and the well-studied Steane, rotated surface, and 4.8.8/6.6.6 color codes for $Z$ only noise. Numerical simulations demonstrate a 20% improvement in the code-capacity threshold for color codes with boundaries by avoiding the mapping from color codes to surface codes. We identify trellis edge number as a key metric of difficulty of decoding, allowing us to quantify the advantage of single-axis ( $X$ or $Z$ ) decoding for Calderbank–Steane–Shor codes and block decoding for concatenated codes.
{"title":"Trellis Decoding for Qudit Stabilizer Codes and Its Application to Qubit Topological Codes","authors":"Eric Sabo;Arun B. Aloshious;Kenneth R. Brown","doi":"10.1109/TQE.2024.3401857","DOIUrl":"https://doi.org/10.1109/TQE.2024.3401857","url":null,"abstract":"Trellis decoders are a general decoding technique first applied to qubit-based quantum error correction codes by Ollivier and Tillich in 2006. Here, we improve the scalability and practicality of their theory, show that it has strong structure, extend the results using classical coding theory as a guide, and demonstrate a canonical form from which the structural properties of the decoding graph may be computed. The resulting formalism is valid for any prime-dimensional quantum system. The modified decoder works for any stabilizer code \u0000<inline-formula><tex-math>$S$</tex-math></inline-formula>\u0000 and separates into two parts: 1) a one-time offline computation that builds a compact graphical representation of the normalizer of the code, \u0000<inline-formula><tex-math>$mathcal {S}^{perp}$</tex-math></inline-formula>\u0000 and 2) a quick, parallel, online query of the resulting vertices using the Viterbi algorithm. We show the utility of trellis decoding by applying it to four high-density length-20 stabilizer codes for depolarizing noise and the well-studied Steane, rotated surface, and 4.8.8/6.6.6 color codes for \u0000<inline-formula><tex-math>$Z$</tex-math></inline-formula>\u0000 only noise. Numerical simulations demonstrate a 20% improvement in the code-capacity threshold for color codes with boundaries by avoiding the mapping from color codes to surface codes. We identify trellis edge number as a key metric of difficulty of decoding, allowing us to quantify the advantage of single-axis (\u0000<inline-formula><tex-math>$X$</tex-math></inline-formula>\u0000 or \u0000<inline-formula><tex-math>$Z$</tex-math></inline-formula>\u0000) decoding for Calderbank–Steane–Shor codes and block decoding for concatenated codes.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-30"},"PeriodicalIF":0.0,"publicationDate":"2024-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10531666","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141439505","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 : 2024-03-16DOI: 10.1109/TQE.2024.3402085
Willers Yang;Patrick Rall
In superconducting architectures, limited connectivity remains a significant challenge for the synthesis and compilation of quantum circuits. We consider models of entanglement-assisted computation where long-range operations are achieved through injections of large Greenberger–Horne–Zeilinger (GHZ) states. These are prepared using ancillary qubits acting as an “entanglement bus,” unlocking global operation primitives such as multiqubit Pauli rotations and fan-out gates. We derive bounds on the circuit size for several well-studied problems, such as CZ circuit, CX circuit, and Clifford circuit synthesis. In particular, in an architecture using one such entanglement bus, we give a synthesis scheme for arbitrary Clifford operations requiring at most $2n+1$ layers of entangled state injections, which can be computed classically in $O(n^{3})$ time. In a square-lattice architecture with two entanglement buses, we show that a graph state can be synthesized using at most $lceil frac{1}{2}nrceil +1$ layers of GHZ state injections, and Clifford operations require only $lceil frac{3}{2} n rceil + O(sqrt{n})$ layers of GHZ state injections.
{"title":"Harnessing the Power of Long-Range Entanglement for Clifford Circuit Synthesis","authors":"Willers Yang;Patrick Rall","doi":"10.1109/TQE.2024.3402085","DOIUrl":"https://doi.org/10.1109/TQE.2024.3402085","url":null,"abstract":"In superconducting architectures, limited connectivity remains a significant challenge for the synthesis and compilation of quantum circuits. We consider models of entanglement-assisted computation where long-range operations are achieved through injections of large Greenberger–Horne–Zeilinger (GHZ) states. These are prepared using ancillary qubits acting as an “entanglement bus,” unlocking global operation primitives such as multiqubit Pauli rotations and fan-out gates. We derive bounds on the circuit size for several well-studied problems, such as CZ circuit, CX circuit, and Clifford circuit synthesis. In particular, in an architecture using one such entanglement bus, we give a synthesis scheme for arbitrary Clifford operations requiring at most \u0000<inline-formula><tex-math>$2n+1$</tex-math></inline-formula>\u0000 layers of entangled state injections, which can be computed classically in \u0000<inline-formula><tex-math>$O(n^{3})$</tex-math></inline-formula>\u0000 time. In a square-lattice architecture with two entanglement buses, we show that a graph state can be synthesized using at most \u0000<inline-formula><tex-math>$lceil frac{1}{2}nrceil +1$</tex-math></inline-formula>\u0000 layers of GHZ state injections, and Clifford operations require only \u0000<inline-formula><tex-math>$lceil frac{3}{2} n rceil + O(sqrt{n})$</tex-math></inline-formula>\u0000 layers of GHZ state injections.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"5 ","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2024-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10531653","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141448003","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}
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