A5053597432- Quantum Computing Algorithms and Architecture
- Quantum Information and Cryptography
- Quantum and electron transport phenomena
- Advanced Bandit Algorithms Research
- Diamond and Carbon-based Materials Research
- Quantum Mechanics and Applications
- Quantum-Dot Cellular Automata
- Machine Learning and Algorithms
- Quantum many-body systems
- Advanced Materials Characterization Techniques
- Low-power high-performance VLSI design
- Stochastic Gradient Optimization Techniques
Quantum Technologies (Sweden)
2025
The University of Tokyo
2021-2024
Yokohama National University
2018-2019
To explore the possibilities of a near-term intermediate-scale quantum algorithm and long-term fault-tolerant computing, fast versatile circuit simulator is needed. Here, we introduce Qulacs, for circuits intended research purpose. We show main concepts explain how to use its features via examples, describe numerical techniques speed-up simulation, demonstrate performance with benchmarks.
Neutral atoms are among the leading platforms toward realizing fault-tolerant quantum computation (FTQC). However, scaling up a single neutral-atom device beyond <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><a:msup><a:mn>10</a:mn><a:mn>4</a:mn></a:msup></a:math> to meet demands of FTQC for practical applications remains challenge. To overcome this challenge, we clarify criteria and technological requirements further based on multiple neutral atom...
Abstract Optimizing parameterized quantum circuits is a key routine in using near-term devices. However, the existing algorithms for such optimization require an excessive number of quantum-measurement shots estimating expectation values observables and repeating many iterations, whose cost has been critical obstacle practical use. We develop efficient alternative algorithm, stochastic gradient line Bayesian (SGLBO), to address this problem. SGLBO reduces measurement-shot by appropriate...
Recent work [M. J. Gullans , ] has shown that quantum error correcting codes defined by random Clifford encoding circuits can achieve a nonzero rate in errors even if the on <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mi>n</a:mi></a:math> qubits, embedded one spatial dimension (1D), have logarithmic depth <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mi>d</b:mi><b:mo>=</b:mo><b:mi>O</b:mi><b:mo>(</b:mo><b:mo...
The variational quantum eigensolver (VQE) is an algorithm to find eigenenergies and eigenstates of systems in chemistry many-body physics. VQE one the most promising applications near-term devices investigate such systems. Here we propose extension calculate nonadiabatic couplings molecules chemical Berry's phase Both quantities play important role understanding properties a system beyond naive adiabatic picture, e.g., dynamics topological matter. We provide circuits classical...
A unitary $t$-design is a powerful tool in quantum information science and fundamental physics. Despite its usefulness, only approximate implementations were known for general $t$. In this paper, we provide the first time circuits that generate exact $t$-designs any $t$ on an arbitrary number of qubits. Our construction inductive practical use small systems. We then introduce $t$-th order generalization randomized benchmarking ($t$-RB) as application $2t$-designs. particularly study $2$-RB...
A major challenge in fault-tolerant quantum computation (FTQC) is to reduce both space overhead -- the large number of physical qubits per logical qubit and time long gate sequences gate. We prove that a protocol using non-vanishing-rate low-density parity-check (LDPC) codes, combined with concatenated Steane achieves constant polylogarithmic overhead, even when accounting for non-zero classical time. This offers an improvement over existing constant-space-overhead protocols, which have...
The essential requirement for fault-tolerant quantum computation (FTQC) is the total protocol design to achieve a fair balance of all critical factors relevant its practical realization, such as space overhead, threshold, and modularity. A major obstacle in realizing FTQC with conventional protocols, those based on surface code concatenated Steane code, has been i.e., required number physical qubits per logical qubit. Protocols high-rate low-density parity-check (LDPC) codes gather...
Neutral atoms are among the leading platforms toward realizing fault-tolerant quantum computation (FTQC). However, scaling up a single neutral-atom device beyond $\sim 10^4$ to meet demands of FTQC for practical applications remains challenge. To overcome this challenge, we clarify criteria and technological requirements further based on multiple neutral atom processing units (QPUs) connected through photonic networking links. Our quantitative analysis shows that nanofiber optical cavities...
Recent work [M. J. Gullans et al., Physical Review X, 11(3):031066 (2021)] has shown that quantum error correcting codes defined by random Clifford encoding circuits can achieve a non-zero rate in errors even if the on $n$ qubits, embedded one spatial dimension (1D), have logarithmic depth $d=\mathcal{O}(\log{n})$. However, this was demonstrated only for simple erasure noise model. In work, we discover desired property indeed holds conventional Pauli Specifically, numerically demonstrate...