Article
Multidisciplinary Sciences
Laird Egan, Dripto M. Debroy, Crystal Noel, Andrew Risinger, Daiwei Zhu, Debopriyo Biswas, Michael Newman, Muyuan Li, Kenneth R. Brown, Marko Cetina, Christopher Monroe
Summary: Quantum error correction encodes information into a larger quantum system to protect it, and fault-tolerant circuits are essential for controlling logical qubits and suppressing errors. Experimental demonstration of fault-tolerant circuits for a Bacon-Shor logical qubit with trapped ion qubits shows significant reductions in error rates in the presence of noise. This indicates the potential of fault-tolerant circuits to enable highly accurate logical primitives in current quantum systems, with the possibility of achieving a stabilized logical qubit through improved gate operations and measurements.
Article
Quantum Science & Technology
Ben W. Reichardt
Summary: Researchers have extended quantum error-correction techniques to extract multiple syndromes simultaneously without requiring additional qubits. This method is fast, efficient, and adheres to geometric constraints, and in some cases allows error-correction without additional qubits.
QUANTUM SCIENCE AND TECHNOLOGY
(2021)
Article
Quantum Science & Technology
Wen-Qiang Liu, Hai-Rui Wei, Leong-Chuan Kwek
Summary: Universal quantum entangling gates are crucial for large-scale quantum computation and communication, and this paper presents a simple and effective quantum circuit for their implementation. It also demonstrates the design of polarization CNOT and Toffoli gates using linear optics.
ADVANCED QUANTUM TECHNOLOGIES
(2022)
Article
Quantum Science & Technology
Kianna Wan, Soonwon Choi, Isaac H. Kim, Noah Shutty, Patrick Hayden
Summary: A fault-tolerant quantum computing scheme has been proposed that can be assembled with a small number of experimental components, potentially reducing the engineering challenges of building a large-scale fault-tolerant quantum computer. The scheme has a threshold of 0.39% for depolarizing noise and the logical error rate decays exponentially in the presence of memory errors. This approach is based on a novel procedure for fault-tolerantly preparing three-dimensional cluster states using a single actively controlled qubit and a pair of delay lines.
Article
Computer Science, Theory & Methods
Dawei Jiao, Ying Li
Summary: In this paper, the authors study error correction in the deep sub-threshold regime and estimate the physical error rate required to achieve low logical error rates using few-qubit codes. They also identify error correction circuits that are efficient for biased error operators.
QUANTUM INFORMATION & COMPUTATION
(2022)
Article
Computer Science, Information Systems
Rosie Cane, Daryus Chandra, Soon Xin Ng, Lajos Hanzo
Summary: Experiments conducted on IBM Quantum devices using [4, 2, 2]-encoded gate sequences showed that gate sequences larger than 10 gates can be considered fault-tolerant, although not all circuits met the tolerance criterion. Some circuits exhibited high error rates that could not be mitigated through classical post-selection. The dominant gate errors were found to not be accurately represented by the popular Pauli error model, and the fault tolerance criterion is best assessed when circuits are restricted to low-dimensional output states.
Article
Quantum Science & Technology
Sven Jandura, Jeff D. Thompson, Guido Pupillo
Summary: Researchers introduced a new gate sequence that is robust against intensity inhomogeneity and Doppler shifts, reducing the sensitivity of gate operations in neutral-atom qubits to experimental imperfections. The gates outperform existing ones for moderate or large imperfections, and show improved performance even for very small imperfections when applied to erasure-biased qubits based on metastable 171Yb.
Article
Multidisciplinary Sciences
Tatsuya Tomaru, Chihiro Yoshimura, Hiroyuki Mizuno
Summary: This article presents a solution for surface code operation on sparse qubit arrays by placing qubits on the edges and nodes of a two-dimensional grid and dividing them into different groups. This makes surface code applicable to sparse arrays.
SCIENTIFIC REPORTS
(2022)
Article
Physics, Multidisciplinary
Kosuke Mitarai, Keisuke Fujii
Summary: The study demonstrates a method to simulate certain types of non-local operations by sampling a set of local operations, which can be used to evaluate the expectation value of observables in a quantum circuit. It also proposes a strategy to decompose a two-qubit gate into a sequence of single-qubit operations, enabling more efficient operations in quantum computing.
NEW JOURNAL OF PHYSICS
(2021)
Article
Quantum Science & Technology
Sven Jandura, Guido Pupillo
Summary: In this study, we identify time-optimal laser pulses for implementing the controlled-Z gate and its generalization, the C(2)Z gate, for Rydberg atoms. The pulses are optimized using quantum optimal control techniques, resulting in smooth waveforms with only a few variational parameters. The short gate duration helps mitigate errors while achieving theoretical gate fidelities compatible with error correction.
Article
Optics
He Wang, Jin Wang
Summary: In this paper, we investigate nonstationary behavior in a fully connected qubit network using a random unitary evolution model. We observe that the environmental effect is reflected in the partial swap interaction between qubits. The nonstationary oscillatory state encoding memory of the initial state indicates the presence of a continuous time crystal phase. We also demonstrate the widespread occurrence of this nonstationary behavior in our model due to the generalized dynamical symmetry. Remarkably, the constructed time crystal phase shows robustness to most types of noise.
Article
Quantum Science & Technology
Y. Kojima, T. Nakajima, A. Noiri, J. Yoneda, T. Otsuka, K. Takeda, S. Li, S. D. Bartlett, A. Ludwig, A. D. Wieck, S. Tarucha
Summary: We demonstrate a scheme for quantum teleportation of single-electron spin qubit in a triple quantum dot using direct Bell measurement and the Pauli exclusion principle. The single spin polarization is teleported from the input qubit to the output qubit, with fidelity primarily limited by singlet-triplet mixing, which can be improved by optimizing the device parameters. These results may be extended to quantum algorithms with a larger number of semiconductor spin qubits.
NPJ QUANTUM INFORMATION
(2021)
Article
Physics, Multidisciplinary
Patrick Barthel, Patrick H. Huber, Jorge Casanova, Inigo Arrazola, Dorna Niroomand, Theeraphot Sriarunothai, Martin B. Plenio, Christof Wunderlich
Summary: We demonstrate the experimental implementation of a two-qubit phase gate using a radio frequency controlled trapped-ion quantum processor. The gate is generated by applying a pulsed dynamical decoupling sequence to the ions' carrier transitions, allowing for tunable and high-fidelity phase shift. The gate's performance is robust against various sources of error and holds potential for fast gate speeds.
NEW JOURNAL OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
Yotam Shapira, Sapir Cohen, Nitzan Akerman, Ady Stern, Roee Ozeri
Summary: In this study, we enhance the fidelity and robustness of entangling gates in quantum computers by introducing spin-dependent squeezing.
PHYSICAL REVIEW LETTERS
(2023)
Article
Quantum Science & Technology
Guoming Wang, Sukin Sim, Peter D. Johnson
Summary: Quantum computing is believed to have significant applications in simulating chemistry and materials. However, preparing high-quality approximations of the ground state is a critical challenge. In this work, a method called "ground state boosting" is introduced, which uses a limited-depth quantum circuit to reliably increase the overlap with the ground state. The performance of a specific type of booster is demonstrated through numerical simulations.
