On-site localization of excitations

2005 ◽  
Vol 5 (4&5) ◽  
pp. 335-349
Author(s):  
M.I. Dykman ◽  
L.F. Santos ◽  
M. Shapiro ◽  
F. .M. Izrailev
Keyword(s):  
Quantum Computer ◽  
Infinite Chain ◽  
Quantum Operations ◽  
Site Localization ◽  
Excitation State ◽  
Coupled Qubits

We demonstrate that, in a quantum computer with perpetually coupled qubits, all excitations can be confined to their sites (qubits) even without refocusing. The on-site localization is obtained by constructing a sequence of qubit energies that efficiently suppresses resonant hopping. The time during which a many-excitation state remains strongly localized in an infinite chain can exceed the reciprocal hopping frequency by $\agt 10^5$ already for a moderate bandwidth of qubit energies. The proposed energy sequence is also convenient for performing quantum operations on the qubits.

scholarly journals Next steps of quantum transport in Majorana nanowire devices

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Hao Zhang ◽  
Dong E. Liu ◽  
Michael Wimmer ◽  
Leo P. Kouwenhoven
Keyword(s):  
Material Science ◽  
Quantum Computer ◽  
Condensed Matter ◽  
Fundamental Aspect ◽  
Semiconductor Nanowire ◽  
Quantum Operations ◽  
Zero Modes ◽  
Ongoing Effort ◽  
Gate Control ◽  
Near Term

Abstract Majorana zero modes are localized quasiparticles that obey non-Abelian exchange statistics. Braiding Majorana zero modes forms the basis of topologically protected quantum operations which could, in principle, significantly reduce qubit decoherence and gate control errors at the device level. Therefore, searching for Majorana zero modes in various solid state systems is a major topic in condensed matter physics and quantum computer science. Since the first experimental signature observed in hybrid superconductor-semiconductor nanowire devices, this field has witnessed a dramatic expansion in material science, transport experiments and theory. While making the first topological qubit based on these Majorana nanowires is currently an ongoing effort, several related important transport experiments are still being pursued in the near term. These will not only serve as intermediate steps but also show Majorana physics in a more fundamental aspect. In this perspective, we summarize these key Majorana experiments and the potential challenges.

ON THE QUANTUM KOLMOGOROV COMPLEXITY OF CLASSICAL STRINGS

2009 ◽  
Vol 07 (04) ◽  
pp. 701-711 ◽  
Author(s):  
MARKUS MÜLLER
Keyword(s):  
Kolmogorov Complexity ◽  
Quantum Computer ◽  
Mathematical Proof ◽  
Minimal Length ◽  
Additive Constant ◽  
Quantum Operations ◽  
Universal Quantum ◽  
Probabilistic Error ◽  
Quantum Complexity ◽  
Binary Strings

We show that classical and quantum Kolmogorov complexity of binary strings agree up to an additive constant. Both complexities are defined as the minimal length of any (classical resp. quantum) computer program that outputs the corresponding string. It follows that quantum complexity is an extension of classical complexity to the domain of quantum states. This is true even if we allow a small probabilistic error in the quantum computer's output. We outline a mathematical proof of this statement, based on an inequality for outputs of quantum operations and a classical program for the simulation of a universal quantum computer.

scholarly journals An efficient simulation for quantum secure multiparty computation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kartick Sutradhar ◽  
Hari Om
Keyword(s):  
Quantum Communication ◽  
Quantum Computer ◽  
Cost Effective ◽  
Secure Multiparty Computation ◽  
Multiparty Computation ◽  
Quantum Operations ◽  
Efficient Simulation ◽  
Quantum Summation ◽  
Quantum Phenomena ◽  
Threshold Approach

AbstractThe quantum secure multiparty computation is one of the important properties of secure quantum communication. In this paper, we propose a quantum secure multiparty summation (QSMS) protocol based on (t, n) threshold approach, which can be used in many complex quantum operations. To make this protocol secure and realistic, we combine both the classical and quantum phenomena. The existing protocols have some security and efficiency issues because they use (n, n) threshold approach, where all the honest players need to perform the quantum multiparty summation protocol. We however use a (t, n) threshold approach, where only t honest players need to compute the quantum summation protocol. Compared to other protocols our proposed protocol is more cost-effective, realistic, and secure. We also simulate it using the IBM corporation’s online quantum computer, or quantum experience.

How to localize excitations in a quantum computer with perpetually coupled qubits

2004 ◽  
Author(s):  
Mark I. Dykman ◽  
Lea F. Santos ◽  
Michael Shapiro ◽  
Felix M. Izrailev
Keyword(s):  
Quantum Computer ◽  
Coupled Qubits

scholarly journals Targeting Molecular Quantum Memory with Embedded Error Correction

2021 ◽  
Author(s):  
Selena Lockyer ◽  
Alessandro Chiesa ◽  
Grigore A. Timco ◽  
Thomas M Bennett ◽  
Inigo Vitorica-Yrzebal ◽  
...  
Keyword(s):  
Error Correction ◽  
Quantum Computer ◽  
Fault Tolerant ◽  
Environmental Noise ◽  
Quantum Memory ◽  
Quantum Operations

The implementation of a quantum computer requires both to protect information from environmental noise and to implement quantum operations efficiently. Achieving this by a fully fault-tolerant platform, in which quantum...

Universal quantum circuit for n-qubit quantum gate: a programmable quantum gate

2007 ◽  
Vol 7 (3) ◽  
pp. 228-242
Author(s):  
P.B.M. Sousa ◽  
R.V. Ramos
Keyword(s):  
Quantum Computer ◽  
Quantum Circuit ◽  
Quantum Gate ◽  
Quantum Circuits ◽  
Unitary Matrices ◽  
Quantum Operations ◽  
Universal Quantum ◽  
Np Problems ◽  
Universal Quantum Circuit ◽  
Specific Quantum

Quantum computation has attracted much attention, among other things, due to its potentialities to solve classical NP problems in polynomial time. For this reason, there has been a growing interest to build a quantum computer. One of the basic steps is to implement the quantum circuit able to realize a given unitary operation. This task has been solved using decomposition of unitary matrices in simpler ones till reach quantum circuits having only single-qubits and CNOTs gates. Usually the goal is to find the minimal quantum circuit able to solve a given problem. In this paper we go in a different direction. We propose a general quantum circuit able to implement any specific quantum circuit by just setting correctly the parameters. In other words, we propose a programmable quantum circuit. This opens the possibility to construct a real quantum computer where several different quantum operations can be realized in the same hardware. The configuration is proposed and its optical implementation is discussed.

scholarly journals Encoding Two-Qubit Logical States and Quantum Operations Using the Energy States of a Physical System

Technologies ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 1
Author(s):  
Dimitrios Ntalaperas ◽  
Nikos Konofaos
Keyword(s):  
Quantum Computer ◽  
Quantum Systems ◽  
Quantum States ◽  
Discrete Energy ◽  
Quantum Operations ◽  
Single Qubit ◽  
Use Of Resources ◽  
Energy States ◽  
Qubit Operations ◽  
Charge Degree

In this paper, we introduce a novel coding scheme, which allows single quantum systems to encode multi-qubit registers. This allows for more efficient use of resources and the economy in designing quantum systems. The scheme is based on the notion of encoding logical quantum states using the charge degree of freedom of the discrete energy spectrum that is formed by introducing impurities in a semiconductor material. We propose a mechanism of performing single qubit operations and controlled two-qubit operations, providing a mechanism for achieving these operations using appropriate pulses generated by Rabi oscillations. The above architecture is simulated using the Armonk single qubit quantum computer of IBM to encode two logical quantum states into the energy states of Armonk’s qubit and using custom pulses to perform one and two-qubit quantum operations.

Dual Port RAM MBIST Failure Analysis Using Time Resolved Dynamic Laser Stimulation

2008 ◽  
Author(s):  
Jonathan Shaw ◽  
Christopher McMahon ◽  
Yin Shyang Ng ◽  
Félix Beaudoi
Keyword(s):  
Failure Analysis ◽  
Embedded Memory ◽  
Complementary Information ◽  
Time Resolved ◽  
Laser Stimulation ◽  
Specific Indication ◽  
Read Operation ◽  
Site Localization

Abstract This paper presents the use of Dynamic Laser Stimulation (DLS) and Time-Resolved DLS (TR-DLS) to provide fail site localization and complementary information on a failed embedded memory IC. In this study, an embedded dual port RAM within a 90nm IC that failed one of the Memory Built-In Self Tests (MBISTs) was investigated. This technique rapidly localized the failing area within the memory read/write circuitry. The TR-DLS provided maps for each operation of the MBIST pattern. With this information, the failure was clearly identified as a read operation failure. The TR-DLS technique also provided much refined site signature (down to just one net) within the sense amp of the Port B of the dual port RAM. This information provided very specific indication on how to improve the operation of that particular sense amp circuitry within the dual port RAM Memory.

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