• 한국초전도ㆍ저온공학회논문지
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• 제16권4호
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• pp.40-43
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• 2014

Quantum information processing using superconducting qubit based on Josephson junction has become one of the most promising candidates for possible realization of a quantum computer. In the heart of the qubit circuits, the superconducting microwave resonator plays a key role in quantum operations and measurements, which enables single-photon level microwave quantum optics. During last decade, the coherence time, or the lifetime of the quantum state, of the superconducting qubit has been dramatically improved. Among several technological innovations, the improvement of superconducting microwave resonator's quality has been the main driving force in getting the qubit performance almost ready for elementary quantum computing architecture. In this paper, I will briefly review very recent progresses of the superconducting microwave resonators especially aimed for quantum device applications during the last decade. The progresses have been driven by ingenious circuit design, material improvement, and new measurement techniques. Even a rather radical idea of three-dimensional large resonators have been successfully implemented in a qubit circuit. All those efforts contributed to our understanding of the qubit decoherence mechanism and as a result to the improvement of qubit performance.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2008년도 High Temperature Superconductivity Vol.XVIII
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• pp.8-8
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• 2008

• 한국전자통신학회논문지
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• 제14권5호
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• pp.907-916
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• 2019

본 논문은 CNOT 게이트만을 사용해 모든 다중비트플립 오류들로부터 표적큐비트를 완벽하게 보호할 수 있는 새로운 5-큐비트 다중비트플립코드를 제안하였다. 제안한 다중비트플립코드는 기존의 단일비트플립코드에서와 같이 근원오류부에 Hadamard 게이트 쌍들을 임베딩 할 경우에 쉽게 다중위상플립코드로 확장될 수 있다. 본 논문의 다중비트플립코드와 다중위상플립코드는 4 개 보조큐비트들에 의한 상태벡터 오류정보를 공유한다. 이 4-큐비트 상태벡터들은 Pauli X와 Z 정정이 수반되는 모든 다중플립오류들이 특정 근원오류를 공통으로 포함하는 특성을 반영한다. 이 특성을 이용해 본 논문은 Pauli X와 Z 근원오류의 검출과 정정을 단 3개의 CNOT 게이트로 배치 처리함으로써 다중플립 오류정정을 위한 QECC 설계에도 불구하고 저비용 실현이 가능함을 보였다. 본 논문이 제안한 5-큐비트 다중비트플립코드와 다중위상플립코드는 100% 오류정정율과 50% 오류판별율 특성을 보였다. 이 논문에 제시된 모든 QECC는 QCAD 시뮬레이터를 사용해 검증되었다.

• 한국초전도ㆍ저온공학회논문지
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• 제21권1호
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• pp.6-9
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• 2019

Developing a gate-tunable, scalable, and topologically-protectable supercurrent qubit and integrating it into a quantum circuit are crucial for applications in the fields of quantum information technology and topological phenomena. Here we propose that the nano-hybrid supercurrent transistors, a superconducting quantum analogue of a transistor, made of topological insulator nanowire would be a promising platform for unprecedented control of both the supercurrent magnitude and the current-phase relation by applying a voltage on a gate electrode. We believe that our experimental design will help probing Majorana state in topological insulator nanowire and establishing a solid-state platform for topological supercurrent qubit.

• 한국광학회:학술대회논문집
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• 한국광학회 2008년도 동계학술발표회 논문집
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• pp.411-412
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• 2008

• Journal of Information Processing Systems
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• 제14권6호
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• pp.1331-1346
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• 2018

Aiming at the problem that the gradient-based edge detection operators are sensitive to the noise, causing the pseudo edges, a triqubit-state measurement-based edge detection algorithm is presented in this paper. Combing the image local and global structure information, the triqubit superposition states are used to represent the pixel features, so as to locate the image edge. Our algorithm consists of three steps. Firstly, the improved partial differential method is used to smooth the defect image. Secondly, the triqubit-state is characterized by three elements of the pixel saliency, edge statistical characteristics and gray scale contrast to achieve the defect image from the gray space to the quantum space mapping. Thirdly, the edge image is outputted according to the quantum measurement, local gradient maximization and neighborhood chain code searching. Compared with other methods, the simulation experiments indicate that our algorithm has less pseudo edges and higher edge detection accuracy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권7호
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• pp.3116-3133
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• 2020

Based on the teleportation by quantum walk, a quantum secret sharing scheme with credible authentication is proposed. Using the Hash function and quantum local operation, combined with the two-step quantum walks circuit on the line, the identity authentication and the teleportation of the secret information in distribution phase are realized. Participants collaborate honestly to recover secret information based on particle measurement results, preventing untrusted agents and external attacks from obtaining useful information. Due to the application of quantum walk, the sender does not need to prepare the necessary entangled state in advance, simply encodes the information to be sent in the coin state, and applies the conditional shift operator between the coin space and the position space to produce the entangled state necessary for quantum teleportation. Security analysis shows that the protocol can effectively resist intercept/resend attacks, entanglement attacks, participant attacks, and impersonation attacks. In addition, the quantum walk circuit used has been implemented in many different physical systems and experiments, so this quantum secret sharing scheme may be achievable in the future.