• Journal of Communications and Networks
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• 제10권3호
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• pp.316-330
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• 2008

This paper proposes a novel method for transporting various types of user traffic effectively over the next generation network called integrated services digital network 3 (ISDN3) (or quantum network) using quantum packets. Basically, a quantum packet comprises one or more 53-byte quanta as generated by a "quantumization" process. While connection-oriented traffic is supported by fixed-size quantum packets each with one quantum to emulate circuit switching, connectionless traffic (e.g., IP packets and active packets) is carried by variable-size quantum packets with multiple quanta to support store-and-forward switching/routing. Our aim is to provide frame-like or datagram-like services while enabling cell-based multiplexing. The quantum packet method also establishes a flexible and extensible framework that caters for future packetization needs while maintaining backward compatibility with ATM. In this paper, we discuss the design of the quantum packet method, including its format, the "quantumization" process, and support for different types of user traffic. We also present an analytical model to evaluate the consumption of network resources (or network costs) when quantum packets are employed to transfer loss-sensitive data using three different approaches: cut-through, store-and-forward and ideal. Close form mathematical expressions are obtained for some situations. In particular, in terms of network cost, we discover two interesting equivalence phenomena for the cut-through and store-and-forward approaches under certain conditions and assumptions. Furthermore, analytical and simulation results are presented to study the system behavior. Our analysis provides valuable insights into the. design of the ISDN3/quantum network.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.13-15
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• 1999

A Josephson sampler circuit using high-Tc superconductor (HTS) ramp-edge junctions has been designed, fabricated, and experimentally tested. It consists of five ramp-edge junctions with a stacked groundplane and is based on single-flux-quantum (SFQ) operations. The sampler was used to measure current waveforms at picosecond and microampere resolutions. We are developing a system based on the sampler for measuring the current waveform in a room-temperature sample. And measuring current flowing through wiring in a semiconductor large-scale integrated circuit is a promising application for the HTS sampler system.

• Progress in Superconductivity
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• 제1권2호
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• pp.81-84
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• 2000

A Josephson sampler circuit using high-Tc superconductor (HTS) ramp-edge junctions has been designed, fabricated, and experimentally tested. It consists of five ramp-edge junctions with a stacked groundplane and is based on single-flux-quantum (SFQ) operations. The sampler was used to measure current waveforms at picosecond and microampere resolutions. We are developing a system based on the sampler for measuring the current waveform in a room-temperature sample. And measuring current flowing through wiring in a semiconductor large-scale integrated circuit is a promising application for the HTS sampler system.

• 한국초전도ㆍ저온공학회논문지
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• 제22권4호
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• pp.10-13
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• 2020

High-quality superconducting coplanar waveguide (SCPW) resonators are crucial for developing superconducting quantum information devices and sensors. We designed quarter-wavelength SCPW resonators and fabricated the SCPW resonators using Nb thin film. The resonant characteristics were measured at T = 4.2 K, revealing the intrinsic quality factor and the coupling quality factor to be Qi = 4,784 and Qc = 17, 980, respectively. Our design and fabrication techniques would be very useful to develop a gate-tunable superconducting qubit based on the semiconductor nanostructures.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.249.2-249.2
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• 2015

Connecting two or more sub-cells is a simple and effective way of improving power conversion efficiency (PCE) of solar cells, and the theoretical efficiency of this tandem cell is known to reach 85~88% of the sum of the sub-cell's efficiencies. There are two ways of connecting sub-cells in the tandem structure, i.e. parallel and series connection. The parallel connection can increase the short circuit current (Jsc) and the series connection can increase the open circuit voltage (Voc). Although various tandem structures have been studied, the full use of incident light and optimization of cell efficiency is still limited. In this work, we designed series tandem solar cells consisting of lead sulfide (PbS) quantum dots/zinc oxide-based QDSC and zinc phthalocyanine (ZnPc)/C60-based small molecule OSCs. It is expected that the loss of the incident light is minimized because the absorption range of the PbS quantum dots and ZnPc is significantly different, and the Voc increases according to the Kirchhoff's law.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.133-133
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• 1999

We have fabricated and tested a simple circuit of the rapid single-flux-quantum(RSFQ) four-stage shift register using a single layer high-T$_c$ superconducting (HTS) YBa$_2Cu_3O_{7-x}$ (YBCO) thin film structure with 9 step-edge Josephson junctions. The circuit includes two read superconducting quantum interference devices(SQUID) and four stages. To establish a robust HTS RSFQ device fabrication process, we have focussed the reproducible process of sharp and straight step-edge formation as well as the ratio of film thickness to step height t/h. The spread of step-edge junction parameters was measured from each13 junctions with t/h=l/3, l/2, and 2/3 at various temperatures. We have demonstrated the simplified operation of the shift register at 65 K..

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.189-192
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• 2000

We fabricated rapid single-flux-quantum RS flip-flop circuits with and without Y$_1$Ba$_2$Cu$_3$O$_{7-{\delta}}$(YBCO) ground plane. The circuit consists of SNS-type ramp-edge Josephson junctions that have cobalt-doped YBCO and Sr$_2$AITaO$_6$(SAT) for barrier layer and insulator layer, respectively. The fabricated Josephson junction showed a typical RSJ-like current-voltage(I-V) characteristics above 50K. We sucessfuly demonstrated RS flip-flop at temperatures around 50K. The RS flip-flop fabricated on ground plane showed more definite set and reset state in voltage-flux(V-${\phi}$) modulation curve for read SQUID, which may be attributed to a shielding effect of the YBCO ground plane.

• 전기전자학회논문지
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• 제27권1호
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• pp.12-18
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• 2023

각각의 큐빗(qubit)을 개별적으로 상온의 제어 회로에 연결하는 현재의 회로 기술은 양자 컴퓨터의 확장성, 신뢰성을 갖추는 데 있어 한계를 가지고 있으며, 집적도 측면에서 극저온의 CMOS 기술 기반 인터커넥트 회로 기술을 통해 기존 기술 대비 인터커넥트의 복잡도, 시스템 안정도 및 사이즈, 그리고 가격 경쟁력을 획기적으로 개선할 수 있을 것으로 기대되고 있다. 외부의 전기적 자극에 민감하며 양자 상태를 일정 시간 이상 유지할 수 없는 큐빗의 특성으로 인한 문제를 극복하고, 확장성과 신뢰성을 양자 컴퓨터 실현을 위한 CMOS 기술 기반 집적화된 센싱 및 제어 회로 기술에 대해 소개한다.

• ETRI Journal
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• 제45권3호
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• pp.462-478
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• 2023

In quantum computing, the use of Pauli frames through software traces of classical computers improves computation efficiency. In previous studies, error correction and Pauli operation tracking have been performed simultaneously using integrated Pauli frames in the physical layer. In such a complex processing structure, the number of simultaneous operations processed in the physical layer exponentially increases as the distance of the surface code encoding logical qubit increases. This study proposes a Pauli frame management architecture partitioned into two layers for a lattice surgery-based surface code and describes its structure and operation rules. To evaluate the effectiveness of our method, we generated a random circuit according to the gate ratios constituting the commonly known quantum circuits and compared the generated circuit with the existing Pauli frame and our method. Simulations show a decrease of about 5% over traditional methods. In the case of experiments that only increase the code distance of the logical qubit, it can be seen that the effect of reducing the physical operation through the logical Pauli frame becomes more important.

• 전자공학회논문지A
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• 제32A권4호
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• pp.47-56
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• 1995

In this paper the model of the MQE-IMD-based neural trigger circuit is improved, where MQW-IMD is a new semiconductor device proposed and experimentally demonstrated by the author for the hardware implementation of the neural networks. The electron energy of AlXGa1-XAsbarrier is calculated by Ensemble Monte Carlo simulation according to the variation of Al mole fraction x and the applied electric field, whtich had been roughly estimated in the previous paper because of the difficulty to get the data. And in the consideration of the tunneling of the confined electrons within the quantum well the accuracy of the impact ionization rate is enhaned. Finally, the dependance of the frequency of pulse-train on the number of quantum wells can be calculated by modelling the effect of the distance of the induced positive charge from the cathode on the electric field at the cathode.