scholarly journals Quantum Computing in Decoherence-Free Subspace Constructed by Triangulation

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Qiao Bi ◽  
Liu Guo ◽  
H. E. Ruda
Keyword(s):  
Quantum Computing ◽  
Kinetic Equation ◽  
Quantum States ◽  
Logical Operations ◽  
Ideal Quantum ◽  
Decoherence Free Subspace ◽  
Decoherence Free Subspaces

A formalism for quantum computing in decoherence-free subspaces is presented. The constructed subspaces are partial triangulated to an index related to environment. The quantum states in the subspaces are just projected states which are ruled by a subdynamic kinetic equation. These projected states can be used to perform ideal quantum logical operations without decoherence.

scholarly journals Entanglement Polytopes: Multiparticle Entanglement from Single-Particle Information

Science ◽  
2013 ◽  
Vol 340 (6137) ◽  
pp. 1205-1208 ◽  
Author(s):  
Michael Walter ◽  
Brent Doran ◽  
David Gross ◽  
Matthias Christandl
Keyword(s):  
Quantum Computing ◽  
Single Particle ◽  
Local Information ◽  
Geometric Object ◽  
Quantum States ◽  
Many Body ◽  
Arbitrary Size ◽  
Global Entanglement ◽  
Low Levels ◽  
Essential Resource

Entangled many-body states are an essential resource for quantum computing and interferometry. Determining the type of entanglement present in a system usually requires access to an exponential number of parameters. We show that in the case of pure, multiparticle quantum states, features of the global entanglement can already be extracted from local information alone. This is achieved by associating any given class of entanglement with an entanglement polytope—a geometric object that characterizes the single-particle states compatible with that class. Our results, applicable to systems of arbitrary size and statistics, give rise to local witnesses for global pure-state entanglement and can be generalized to states affected by low levels of noise.

scholarly journals Topological Quantum Computing and 3-Manifolds

2021 ◽  
Vol 3 (1) ◽  
pp. 153-165
Author(s):  
Torsten Asselmeyer-Maluga
Keyword(s):  
Quantum Computing ◽  
Berry Phase ◽  
Basic Structure ◽  
Quantum States ◽  
Point Of View ◽  
Surface Topology ◽  
Usual Sense ◽  
Closed Curves ◽  
Topological Quantum ◽  
2D System

In this paper, we will present some ideas to use 3D topology for quantum computing. Topological quantum computing in the usual sense works with an encoding of information as knotted quantum states of topological phases of matter, thus being locked into topology to prevent decay. Today, the basic structure is a 2D system to realize anyons with braiding operations. From the topological point of view, we have to deal with surface topology. However, usual materials are 3D objects. Possible topologies for these objects can be more complex than surfaces. From the topological point of view, Thurston’s geometrization theorem gives the main description of 3-dimensional manifolds. Here, complements of knots do play a prominent role and are in principle the main parts to understand 3-manifold topology. For that purpose, we will construct a quantum system on the complements of a knot in the 3-sphere. The whole system depends strongly on the topology of this complement, which is determined by non-contractible, closed curves. Every curve gives a contribution to the quantum states by a phase (Berry phase). Therefore, the quantum states can be manipulated by using the knot group (fundamental group of the knot complement). The universality of these operations was already showed by M. Planat et al.

A quantum repeater based on decoherence free subspaces

2008 ◽  
Vol 8 (5) ◽  
pp. 468-488
Author(s):  
U. Dorner ◽  
A. Klein ◽  
D. Jaksch
Keyword(s):  
Quantum Communication ◽  
Waiting Times ◽  
Entanglement Swapping ◽  
Quantum Gates ◽  
Quantum Repeater ◽  
Decoherence Free Subspace ◽  
Decoherence Free Subspaces

We study a quantum repeater which is based on decoherence free quantum gates recently proposed by Klein {\it et al.} [Phys. Rev. A, {\bf 73}, 012332 (2006)]. A number of operations on the decoherence free subspace in this scheme makes use of an ancilla qubit, which undergoes dephasing and thus introduces decoherence to the system. We examine how this decoherence affects entanglement swapping and purification as well as the performance of a quantum repeater. We compare the decoherence free quantum repeater with a quantum repeater based on qubits that are subject to decoherence and show that it outperforms the latter when decoherence due to long waiting times of conventional qubits becomes significant. Thus, a quantum repeater based on decoherence free subspaces is a possibility to greatly improve quantum communication over long or even intercontinental distances.

scholarly journals Freezing dynamics of entanglement and nonlocality for qutrit-qutrit (3 ⊗ 3) quantum systems

2019 ◽  
Vol 34 (13) ◽  
pp. 1950102 ◽  
Author(s):  
Mazhar Ali
Keyword(s):  
Finite Time ◽  
Quantum Systems ◽  
Quantum States ◽  
Multipartite Quantum Systems ◽  
Combined Action ◽  
Time Invariant ◽  
Decoherence Free Subspaces

We examine the possibilities of nontrivial phenomena of time-invariant entanglement and freezing dynamics of entanglement for qutrit-qutrit quantum systems. We find no evidence for time-invariant entanglement, however, we do observe that certain quantum states freeze their entanglement after decaying for some time. It is interesting that quantum states are changing whereas their entanglement remains constant. We find that the combined action of decoherence free subspaces and subspaces where quantum states decay, facilitate this phenomenon. This study is an extension of similar phenomena observed for qubit-qubit systems, qubit-qutrit, and multipartite quantum systems. We examine nonlocality of a specific family of states and find the certain instances where the states still remain entangled, however, they can either loose their nonlocality at a finite time or remain nonlocal for all times.

Scalable quantum computing in decoherence-free subspaces with Cooper-pair box qubits

2010 ◽  
Vol 374 (4) ◽  
pp. 539-543 ◽  
Author(s):  
Zhi-Bo Feng ◽  
Hong-Ling Wang ◽  
Hongpei Han ◽  
Run-Ying Yan
Keyword(s):  
Quantum Computing ◽  
Cooper Pair ◽  
Cooper Pair Box ◽  
Decoherence Free Subspaces

scholarly journals One-way quantum computing in a decoherence-free subspace

2007 ◽  
Vol 9 (6) ◽  
pp. 201-201 ◽  
Author(s):  
M S Tame ◽  
M Paternostro ◽  
M S Kim
Keyword(s):  
Quantum Computing ◽  
Decoherence Free Subspace

scholarly journals Enhanced quantum signature scheme using quantum amplitude amplification operators

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258091
Author(s):  
Basma Elias ◽  
Ahmed Younes
Keyword(s):  
Quantum Computing ◽  
Quantum Signature ◽  
Quantum States ◽  
Bell States ◽  
Signature Scheme ◽  
Signature Schemes ◽  
Diffusion Operator ◽  
Quantum Amplitude ◽  
Preparation Phase ◽  
Amplitude Amplification

Quantum signature is the use of the principles of quantum computing to establish a trusted communication between two parties. In this paper, a quantum signature scheme using amplitude amplification techniques will be proposed. To secure the signature, the proposed scheme uses a partial diffusion operator and a diffusion operator to hide/unhide certain quantum states during communication. The proposed scheme consists of three phases, preparation phase, signature phase and verification phase. To confuse the eavesdropper, the quantum states representing the signature might be hidden, not hidden or encoded in Bell states. It will be shown that the proposed scheme is more secure against eavesdropping when compared with relevant quantum signature schemes.

Sign in / Sign up

Export Citation Format

Share Document