THREE-QUBIT QUANTUM ENTANGLEMENT FOR SI (S = 3/2, I = 1/2) SPIN SYSTEM

2011 ◽  
Vol 09 (07n08) ◽  
pp. 1635-1642 ◽  
Author(s):  
A. GÜN ◽  
A. GENÇTEN
Keyword(s):  
Quantum Information ◽  
Spin System ◽  
Quantum Information Processing ◽  
Matrix Representation ◽  
Pulse Sequences ◽  
Logic Gates ◽  
Entangled States ◽  
Spin States ◽  
The Matrix ◽  
Qubit States

In quantum information processing, spin-3/2 electron or nuclear spin states are known as two-qubit states. For SI (S = 3/2, I = 1/2) spin system, there are eight three-qubit states. In this study, first, three-qubit CNOT logic gates are obtained. Then three-qubit entangled states are obtained by using the matrix representation of Hadamard and three-qubit CNOT logic gates. By considering single 31P@C60 molecule as SI (S = 3/2, I = 1/2) spin system, three-qubit entangled states are also obtained using the magnetic resonance pulse sequences of Hadamard and CNOT logic gates.

CONSTRUCTION AND APPLICATION OF FOUR-QUBIT SWAP LOGIC GATE IN NMR QUANTUM COMPUTING

2011 ◽  
Vol 09 (02) ◽  
pp. 779-790 ◽  
Author(s):  
A. GÜN ◽  
I. ŞAKA ◽  
A. GENÇTEN
Keyword(s):  
Quantum Computing ◽  
Spin System ◽  
Matrix Representation ◽  
Pulse Sequence ◽  
Logic Gate ◽  
Logic Gates ◽  
Unitary Matrices ◽  
Quantum Logic Gates ◽  
Product Operator ◽  
The Matrix

In NMR quantum computing, spin states of spin-1/2 nuclei are called qubits. Quantum logic gates are represented by unitary matrices. As a universal gate, controlled-NOT (CNOT) is a two-qubit gate. For the IS (I = 1/2 and S = 1/2) spin system, two-qubit CNOT gate is represented by a 4 × 4 matrix. SWAP logic gate, which exchanges two quantum states, is constructed by CNOT gates. In this study, first, four-qubit CNOT gates are constructed for the IS (I = 3/2, S = 3/2) spin system. Then, by using these CNOT gates, a four-qubit SWAP logic gate is found. As an application and verification, an obtained SWAP logic gate is applied to the matrix representation of product operators for the IS (I = 3/2, S = 3/2) spin system. SWAP logic gate can also be presented by an NMR pulse sequence. By using the product operator theory, the pulse sequence of the SWAP logic gate is applied to product operators of the IS (I = 3/2, S = 3/2) spin system. The expected exchange results are obtained for both the matrix representation and the pulse sequence of SWAP logic gate.

Construction of Two-Ququart Quantum Entanglement by Using Magnetic Resonance Selective Pulse Sequences

2018 ◽  
Vol 73 (10) ◽  
pp. 911-918 ◽  
Author(s):  
Mikail Doğuş Karakaş ◽  
Azmi Gençten
Keyword(s):  
Quantum Computing ◽  
Magnetic Resonance ◽  
Matrix Representation ◽  
Pulse Sequences ◽  
Logic Gates ◽  
Entangled States ◽  
Selective Pulse ◽  
Quantum Numbers ◽  
Dimensional Unit ◽  
Four Levels

AbstractA d-dimensional unit of information in quantum computing is called a qudit. For d = 4 there exist four magnetic quantum numbers of spin-3/2. These four levels can be called ququarts. Then, for the SI (S = 3/2, I = 3/2) spin system, 16 two-ququart states are obtained. In this study, first, two-ququart entangled states are constructed by using matrix representation of Hadamard and CNOT logic gates. Two-ququart entangled states are also constructed by using magnetic resonance selective pulse sequences of Hadamard and CNOT logic gates. Then, a generalised expression is obtained for the transformation of two-qudit entangled states between each other. This expression is applied for two-ququart entangled states.

Manipulation of Entangled States for Quantum Information Processing

2005 ◽  
pp. 49-58 ◽  
Author(s):  
S. Bose ◽  
S. F. Huelga ◽  
D. Jonathan ◽  
P. L. Knight ◽  
M. Murao ◽  
...  
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Entangled States

scholarly journals Optimal verification of general bipartite pure states

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Xiao-Dong Yu ◽  
Jiangwei Shang ◽  
Otfried Gühne
Keyword(s):  
Quantum Information ◽  
Quantum Information Processing ◽  
Optimization Problems ◽  
Optimal Strategies ◽  
Adaptive Strategies ◽  
Quantum States ◽  
Entangled States ◽  
Classical Communication ◽  
Pure States ◽  
Projective Measurements

AbstractThe efficient and reliable verification of quantum states plays a crucial role in various quantum information processing tasks. We consider the task of verifying entangled states using one-way and two-way classical communication and completely characterize the optimal strategies via convex optimization. We solve these optimization problems using both analytical and numerical methods, and the optimal strategies can be constructed for any bipartite pure state. Compared with the nonadaptive approach, our adaptive strategies significantly improve the efficiency of quantum state verification. Moreover, these strategies are experimentally feasible, as only few local projective measurements are required.

Analysing the Efficiencies of Partially Entangled Three-Qubit States for Quantum Information Processing Under Real Conditions

2019 ◽  
Vol 74 (6) ◽  
pp. 523-537
Author(s):  
Jyoti Faujdar ◽  
Atul Kumar
Keyword(s):  
Quantum Information Processing ◽  
Weak Measurement ◽  
Entangled States ◽  
Entangled State ◽  
Maximally Entangled State ◽  
Prepared State ◽  
Noisy Conditions ◽  
Partially Entangled States ◽  
Robust To Noise ◽  
Qubit States

AbstractIn this article, we revisit the question of analysing the efficiencies of partially entangled states in three-qubit classes under real conditions. Our results show some interesting observations regarding the efficiencies and correlations of partially entangled states. Surprisingly, we find that the efficiencies of many three-qubit partially entangled states exceed that of maximally entangled three-qubit states under real noisy conditions and applications of weak measurements. Our analysis, therefore, suggests that the efficiencies of partially entangled states are much more robust to noise than those of maximally entangled states at least for the GHZ (Greenberger–Horne–Zeilinger) class states, for certain protocols; i.e. less correlations in the initially prepared state may also lead to better efficiency and hence one need not always consider starting with a maximally entangled state with maximum correlations between the qubits. For a set of partially entangled states, we find that the efficiency is optimal, independent of the decoherence and state parameters, if the value of weak measurement parameter is very large. For other values of the weak measurement parameter, the robustness of the states depends on the decoherence and state parameters. Moreover, we further show that one can achieve higher efficiencies in a protocol by using non-optimal weak measurement strengths instead of optimal weak measurement strengths.

scholarly journals Realizing a deterministic source of multipartite-entangled photonic qubits

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jean-Claude Besse ◽  
Kevin Reuer ◽  
Michele C. Collodo ◽  
Arne Wulff ◽  
Lucien Wernli ◽  
...  
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Electromagnetic Radiation ◽  
Quantum Information Processing ◽  
Entangled States ◽  
Experimental Setting ◽  
Many Body ◽  
Body State ◽  
Process Tomography ◽  
Multi Mode

Abstract Sources of entangled electromagnetic radiation are a cornerstone in quantum information processing and offer unique opportunities for the study of quantum many-body physics in a controlled experimental setting. Generation of multi-mode entangled states of radiation with a large entanglement length, that is neither probabilistic nor restricted to generate specific types of states, remains challenging. Here, we demonstrate the fully deterministic generation of purely photonic entangled states such as the cluster, GHZ, and W state by sequentially emitting microwave photons from a controlled auxiliary system into a waveguide. We tomographically reconstruct the entire quantum many-body state for up to N = 4 photonic modes and infer the quantum state for even larger N from process tomography. We estimate that localizable entanglement persists over a distance of approximately ten photonic qubits.

scholarly journals Experimental creation of multi-photon high-dimensional layered quantum states

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Xiao-Min Hu ◽  
Wen-Bo Xing ◽  
Chao Zhang ◽  
Bi-Heng Liu ◽  
Matej Pivoluska ◽  
...  
Keyword(s):  
Quantum Information ◽  
Quantum Entanglement ◽  
Quantum State ◽  
Quantum States ◽  
High Dimensional ◽  
Entangled States ◽  
Entangled State ◽  
Quantum Network ◽  
Quantum Networks ◽  
Qubit States

Abstract Quantum entanglement is one of the most important resources in quantum information. In recent years, the research of quantum entanglement mainly focused on the increase in the number of entangled qubits or the high-dimensional entanglement of two particles. Compared with qubit states, multipartite high-dimensional entangled states have beneficial properties and are powerful for constructing quantum networks. However, there are few studies on multipartite high-dimensional quantum entanglement due to the difficulty of creating such states. In this paper, we experimentally prepared a multipartite high-dimensional state $$\left|{\Psi }_{442}\right\rangle =\frac{1}{2}(\left|000\right\rangle +\left|110\right\rangle +\left|221\right\rangle +\left|331\right\rangle )$$ Ψ 442 = 1 2 ( 000 + 110 + 221 + 331 ) by using the path mode of photons. We obtain the fidelity F = 0.854 ± 0.007 of the quantum state, which proves a real multipartite high-dimensional entangled state. Finally, we use this quantum state to demonstrate a layered quantum network in principle. Our work highlights another route toward complex quantum networks.

Correlations, Nonlocality and Usefulness of an Efficient Class of Two-Qubit Mixed Entangled States

2018 ◽  
Vol 73 (3) ◽  
pp. 191-206 ◽  
Author(s):  
Parvinder Singh ◽  
Atul Kumar
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Weak Measurement ◽  
Analytical Relation ◽  
Entangled States ◽  
Mixed States ◽  
New Class ◽  
Chsh Inequality ◽  
Noisy Conditions

AbstractWe establish an analytical relation between the Bell-Clauser-Horne-Shimony-Holt (Bell-CHSH) inequality and weak measurement strengths under noisy conditions. We show that the analytical results obtained in this article are of utmost importance for proposing a new class of two-qubit mixed states for quantum information processing. Our analysis further shows that the states proposed here are better resources for quantum information in comparison to other two-qubit mixed entangled states.

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