Quantum circuit simulation (QCS) is essential in the noisy intermediate scale quantum (NISQ) era when real quantum computers are scarce. However, fully tracking the states of a quantum system in QCS is highly challenging due to the exponential memory growth that significantly limits the computational reach of classical systems for QCS. Though it is straightforward to leverage secondary storage to extend the scale of QCS, excessive data movement between memory and storage dominates the simulation time, making this solution unrealistic. To tackle this challenge, we identify an intrinsic property of QCS and implement an open-source framework to effectively reduce data movement by >116x. We evaluate the framework on various benchmarks and demonstrate 4x memory reduction with only <20% overhead. On a memory constrained system, we show that it extends the scale of QCS to 32 qubits (64 GB memory requirement) while existing simulators are bounded to 28 qubits (4 GB memory requirement). Our implementation can be accessed via https://github.com/Zhaoyilunnn/qdao.
Quantum circuit simulation (QCS) is essential in the noisy intermediate scale quantum (NISQ) era when real quantum computers are scarce. However, fully tracking the states of a quantum system in QCS is highly challenging due to the exponential memory growth that significantly limits the computational reach of classical systems for QCS. Though it is straightforward to leverage secondary storage to extend the scale of QCS, excessive data movement between memory and storage dominates the simulation time, making this solution unrealistic. To tackle this challenge, we identify an intrinsic property of QCS and implement an open-source framework to effectively reduce data movement by >116x. We evaluate the framework on various benchmarks and demonstrate 4x memory reduction with only <20% overhead. On a memory constrained system, we show that it extends the scale of QCS to 32 qubits (64 GB memory requirement) while existing simulators are bounded to 28 qubits (4 GB memory requirement). Our implementation can be accessed via https://github.com/Zhaoyilunnn/qdao.
The trend towards optimization of quantum circuit simulators (QCS) has been driven by the rapid development of quantum computing, as there is a growing interest in creating high-efficiency QCS for quantum computing systems and applications. Despite this growth, the existing classical simulators pose challenges in simulating large quantum operations due to the exponential growth of memory and computation resources required. To overcome these issues, some studies have explored the use of non-volatile memory, such as solid-state disks (SSDs), to store a large amount of state vector while maintaining cost efficiency. However, such highly frequent read-and-write operations in large quantum simulations can quickly deplete the lifespan of SSDs, leading to overestimated practical efficiency and environmental concerns. Alternatively, Remote Direct Memory Access (RDMA) can be used to expand memory capacity, allowing computers in a network to access remote memories with low latency and high bandwidth. Therefore, we propose using one-sided RDMA operations along with a series of optimizations to expand memory capacity and efficiently maximize the utilization of unused memory assets. The experimental results demonstrate that our approaches can be practically scaled up without any lifespan consumption. The proposed optimization can get a 3.0x speedup compared to the local memory approach and a maximum speedup of 2.0x compared to the naive RDMA-based approach, as observed in our benchmark test.
Executing large quantum circuits is not feasible using the currently available NISQ (noisy intermediate-scale quantum) devices. The high costs of using real quantum devices make it further challenging to research and develop quantum algorithms. As a result, performing classical simulations is usually the preferred method for researching and validating large-scale quantum algorithms. However, these simulations require a huge amount of resources, as each additional qubit exponentially increases the computational space required. Distributed Quantum Computing (DQC) is a promising alternative to reduce the resources required for simulating large quantum algorithms at the cost of increased runtime. This study presents a comparative analysis of two simulation methods: circuit-splitting and full-circuit execution using distributed memory, each having a different type of overhead. The first method, using CutQC, cuts the circuit into smaller subcircuits and allows us to simulate a large quantum circuit on smaller machines. The second method, using Qiskit-Aer-GPU, distributes the computational space across a distributed memory system to simulate the entire quantum circuit. Results indicate that full-circuit executions are faster than circuit-splitting for simulations performed on a single node. However, circuit-splitting simulations show promising results in specific scenarios as the number of qubits is scaled.
Full-state quantum circuit simulation requires exponentially increased memory size to store the state vector as the number of qubits scales, presenting significant limitations in classical computing systems. Our paper introduces BMQSim, a novel state vector quantum simulation framework that employs lossy compression to address the memory constraints on graphics processing unit (GPU) machines. BMQSim effectively tackles four major challenges for state-vector simulation with compression: frequent compression/decompression, high memory movement overhead, lack of dedicated error control, and unpredictable memory space requirements. Our work proposes an innovative strategy of circuit partitioning to significantly reduce the frequency of compression occurrences. We introduce a pipeline that seamlessly integrates compression with data movement while concealing its overhead. Additionally, BMQSim incorporates the first GPU-based lossy compression technique with point-wise error control. Furthermore, BMQSim features a two-level memory management system, ensuring efficient and stable execution. Our evaluations demonstrate that BMQSim can simulate the same circuit with over 10 times less memory usage on average, achieving fidelity over 0.99 and maintaining comparable simulation time to other state-of-the-art simulators.
Executing large quantum circuits is not feasible using the currently available NISQ (noisy intermediate-scale quantum) devices. The high costs of using real quantum devices make it further challenging to research and develop quantum algorithms. As a result, performing classical simulations is usually the preferred method for researching and validating large-scale quantum algorithms. However, these simulations require a huge amount of resources, as each additional qubit exponentially increases the computational space required. Distributed Quantum Computing (DQC) is a promising alternative to reduce the resources required for simulating large quantum algorithms at the cost of increased runtime. This study presents a comparative analysis of two simulation methods: circuit-splitting and full-circuit execution using distributed memory, each having a different type of overhead. The first method, using CutQC, cuts the circuit into smaller subcircuits and allows us to simulate a large quantum circuit on smaller machines. The second method, using Qiskit-Aer-GPU, distributes the computational space across a distributed memory system to simulate the entire quantum circuit. Results indicate that full-circuit executions are faster than circuit-splitting for simulations performed on a single node. However, circuit-splitting simulations show promising results in specific scenarios as the number of qubits is scaled.
Large-scale quantum circuit simulation on high-performance computing (HPC) systems is crucial for developing and verifying quantum algorithms to overcome the limitations of current noisy quantum computers. However, existing simulators face scalability bottlenecks due to memory limits and communication overhead. Many state-of-the-art approaches rely on static circuit partitioning, which makes it difficult to address the exponential growth in problem size as the number of qubits increases. To overcome these challenges, we present ScaleQsim, a highly scalable quantum circuit simulation framework for large-scale HPC systems. ScaleQsim focuses on providing a unified representation of the full qubit state, yet provides scalability through efficient synchronization and communication. ScaleQsim adopts a novel full state vector partitioning strategy that evenly distributes the full state vector across multiple nodes and GPUs. This distributed structure enables efficient parallel gate execution without costly synchronization, and ScaleQsim applies adaptive kernel configuration, which adjusts execution parameters based on GPU resources and task granularity to enhance simulation efficiency. Our evaluation on the Perlmutter supercomputer with up to 512 GPUs demonstrates that ScaleQsim simulates quantum circuits with up to 42 qubits and outperforms state-of-the-art simulators by up to 77.40× across various quantum circuits.
Quantum circuits are fundamental components of quantum computing, and state-vector-based quantum circuit simulation is a widely used technique for tracking qubit behavior throughout circuit evolution. However, simulating a circuit with n qubits requires 2n+4 bytes of memory, making simulations of more than 40 qubits feasible only on supercomputers. To address this limitation, we propose the Qu-Trefoil, a system designed for large-scale quantum circuit simulations on an FPGA-based platform called Trefoil. Trefoil is a multi-FPGA system connected to eight storage subsystems, each equipped with 32 SATA disks. Qu-Trefoil integrates a suite of HLS-based universal quantum gates, including Clifford gates (Hadamard (H), Pauli-Z (Z), Phase (S), Controlled-NOT (CNOT)), the T gate, and unitary matrix computation, along with HDL-designed modules for system-wide integration. Our extensive evaluation demonstrates the system's robustness and flexibility, covering quantum gate performance, chunk size, disk extensibility, and efficiency across different SATA generations. We successfully simulated quantum circuits with over 43 qubits, which required more than 128 TB of memory, in approximately 3.72 to 13.06 hours on a single storage subsystem equipped with one FPGA. This achievement represents a significant milestone in the advancement of quantum computing simulations. Furthermore, thanks to its unique architecture, Qu-Trefoil is more accessible, flexible, and cost-efficient than other existing simulators for large-scale quantum circuit simulations, making it a viable option for researchers with limited access to supercomputers.