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.

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.

Realizing an N-two-qubit quantum logic gate in a cavity QED with nearest qubit--qubit interaction

2016 ◽  
Vol 16 (5&6) ◽  
pp. 465-482
Author(s):  
Taoufik Said ◽  
Abdelhaq Chouikh ◽  
Karima Essammouni ◽  
Mohamed Bennai
Keyword(s):  
Quantum Logic ◽  
Cavity Qed ◽  
Logic Gate ◽  
Operation Time ◽  
Logic Gates ◽  
Initial State ◽  
Gate Operation ◽  
Quantum Logic Gates ◽  
Current State ◽  
Phase Gate

We propose an effective way for realizing a three quantum logic gates (NTCP gate, NTCP-NOT gate and NTQ-NOT gate) of one qubit simultaneously controlling N target qubits based on the qubit-qubit interaction. We use the superconducting qubits in a cavity QED driven by a strong microwave field. In our scheme, the operation time of these gates is independent of the number N of qubits involved in the gate operation. These gates are insensitive to the initial state of the cavity QED and can be used to produce an analogous CNOT gate simultaneously acting on N qubits. The quantum phase gate can be realized in a time (nanosecond-scale) much smaller than decoherence time and dephasing time (microsecond-scale) in cavity QED. Numerical simulation under the influence of the gate operations shows that the scheme could be achieved efficiently within current state-of-the-art technology.

scholarly journals Design of Gates for Quantum Computation: The NOT Gate

1997 ◽  
Vol 11 (18) ◽  
pp. 2207-2215
Author(s):  
Dima Mozyrsky ◽  
Vladimir Privman ◽  
Steven P. Hotaling
Keyword(s):  
Quantum Logic ◽  
Logic Gate ◽  
Logic Gates ◽  
Time Dependent ◽  
Practical Realization ◽  
Quantum Logic Gate ◽  
Quantum Logic Gates ◽  
Gate Circuit ◽  
Spatially Extended ◽  
Analog Approach

We offer an alternative to the conventional network formulation of quantum computing. We advance the analog approach to quantum logic gate/circuit construction. As an illustration, we consider the spatially extended NOT gate as the first step in the development of this approach. We derive an explicit form of the interaction Hamiltonian corresponding to this gate and analyze its properties. We also discuss general extensions to the case of certain time-dependent interactions which may be useful for practical realization of quantum logic gates.

Quantum cost optimized design of 4-bit reversible universal shift register using reduced number of logic gate

2018 ◽  
Vol 16 (02) ◽  
pp. 1850016 ◽  
Author(s):  
H. Maity ◽  
A. Biswas ◽  
A. K. Bhattacharjee ◽  
A. Pal
Keyword(s):  
Quantum Computing ◽  
Logic Gate ◽  
Logic Gates ◽  
Reversible Logic ◽  
Shift Register ◽  
Optimized Design ◽  
Quantum Cost ◽  
Universal Shift Register ◽  
Reversible Logic Gates

In this paper, we have proposed the design of quantum cost (QC) optimized 4-bit reversible universal shift register (RUSR) using reduced number of reversible logic gates. The proposed design is very useful in quantum computing due to its low QC, less no. of reversible logic gate and less delay. The QC, no. of gates, garbage outputs (GOs) are respectively 64, 8 and 16 for proposed work. The improvement of proposed work is also presented. The QC is 5.88% to 70.9% improved, no. of gate is 60% to 83.33% improved with compared to latest reported result.

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.

scholarly journals ANALYSIS OF AN EXPERIMENTAL QUANTUM LOGIC GATE BY COMPLEMENTARY CLASSICAL OPERATIONS

2006 ◽  
Vol 21 (24) ◽  
pp. 1837-1850 ◽  
Author(s):  
HOLGER F. HOFMANN ◽  
RYO OKAMOTO ◽  
SHIGEKI TAKEUCHI
Keyword(s):  
Quantum Logic ◽  
Logic Gate ◽  
Bell State ◽  
Logic Gates ◽  
Basis Sets ◽  
Entanglement Generation ◽  
Quantum Logic Gates ◽  
State Discrimination ◽  
Logic Operations

Quantum logic gates can perform calculations much more efficiently than their classical counterparts. However, the level of control needed to obtain a reliable quantum operation is correspondingly higher. In order to evaluate the performance of experimental quantum gates, it is therefore necessary to identify the essential features that indicate quantum coherent operation. In this paper, we show that an efficient characterization of an experimental device can be obtained by investigating the classical logic operations on a pair of complementary basis sets. It is then possible to obtain reliable predictions about the quantum coherent operations of the gate such as entanglement generation and Bell state discrimination even without performing these operations directly.

scholarly journals Introduction to Quantum Gates : Implementation of Single and Multiple Qubit Gates

2021 ◽  
pp. 385-392
Author(s):  
Ropa Roy ◽  
Asoke Nath
Keyword(s):  
Quantum Logic ◽  
Digital Circuits ◽  
Logic Gate ◽  
Logic Gates ◽  
Quantum Circuit ◽  
Quantum Gates ◽  
Quantum Logic Gate ◽  
Quantum Logic Gates ◽  
Classical Computing ◽  
Superposition States

A quantum gate or quantum logic gate is an elementary quantum circuit working on a small number of qubits. It means that quantum gates can grasp two primary feature of quantum mechanics that are entirely out of reach for classical gates : superposition and entanglement. In simpler words quantum gates are reversible. In classical computing sets of logic gates are connected to construct digital circuits. Similarly, quantum logic gates operates on input states that are generally in superposition states to compute the output. In this paper the authors will discuss in detail what is single and multiple qubit gates and scope and challenges in quantum gates.

scholarly journals A quantum-logic gate between distant quantum-network modules

Science ◽  
2021 ◽  
Vol 371 (6529) ◽  
pp. 614-617 ◽  
Author(s):  
Severin Daiss ◽  
Stefan Langenfeld ◽  
Stephan Welte ◽  
Emanuele Distante ◽  
Philip Thomas ◽  
...  
Keyword(s):  
Quantum Logic ◽  
Logic Gate ◽  
Logic Gates ◽  
Photon Detection ◽  
Quantum Networks ◽  
Quantum Logic Gate ◽  
Quantum Logic Gates ◽  
Network Modules ◽  
Nonlocal Quantum ◽  
Efficient Coupling

The big challenge in quantum computing is to realize scalable multi-qubit systems with cross-talk–free addressability and efficient coupling of arbitrarily selected qubits. Quantum networks promise a solution by integrating smaller qubit modules to a larger computing cluster. Such a distributed architecture, however, requires the capability to execute quantum-logic gates between distant qubits. Here we experimentally realize such a gate over a distance of 60 meters. We employ an ancillary photon that we successively reflect from two remote qubit modules, followed by a heralding photon detection, which triggers a final qubit rotation. We use the gate for remote entanglement creation of all four Bell states. Our nonlocal quantum-logic gate could be extended both to multiple qubits and many modules for a tailor-made multi-qubit computing register.

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