In this paper we present improvements to the cost of quantum circuits implemented with 2n-lines circuit implementation. The 2n-line circuit implementation is intended for the linear nearest neighbor quantum circuits and implements any quantum circuits in such manner that they can be directly mapped to quantum implementations. In this paper we propose a replacement strategy for 2- and 3-qubit patterns detected on the control lines. It is demonstrated that application of this strategy leads to a considerable reduction of circuit cost.
In this paper we present improvements to the cost of quantum circuits implemented with 2n-lines circuit implementation. The 2n-line circuit implementation is intended for the linear nearest neighbor quantum circuits and implements any quantum circuits in such manner that they can be directly mapped to quantum implementations. In this paper we propose a replacement strategy for 2- and 3-qubit patterns detected on the control lines. It is demonstrated that application of this strategy leads to a considerable reduction of circuit cost.
This paper presents models for transforming standard reversible circuits into Linear Nearest Neighbor (LNN) architecture without inserting SWAP gates. Templates to optimize the transformed LNN circuits are proposed. All minimal LNN circuits for all 3-qubit functions have been generated to serve as benchmarks to evaluate heuristic optimization algorithms. The minimal results generated are compared with optimized LNN circuits obtained from the post synthesis algorithm --- template matching with LNN templates. Experiments show that the suggested synthesis flow significantly improves the quantum cost of circuits.
Advancements in quantum circuit manufacturing methodologies have exhibited substantial progress over the past decade. One persisting challenge and technological constraint in this domain is the Nearest Neighbour (NN) implementation, necessitating physical qubits to be adjacent. One of the promising solutions to addressing this nearest neighbor problem was recognized, revealing that optimizing the grid selection could lead to a substantial reduction in the conversion cost for nearest neighbors and a more efficient utilization of SWAP operations. We have employed a mapping scheme to situate them effectively within suitable 2D grids. The conversion of quantum circuits into NN-compatible designs demonstrates promising outcomes, surpassing heuristic and meta- heuristic techniques. Through experimental evaluations and comparisons with state-of-the-art methodologies, we have identified significant enhancements. Experimental results exhibit notable breakthroughs, showcasing advancements of approximately 7.63%, 11.76%, 20.5%, 25.46% and 11.56% over existing 2D works. Furthermore, considerable improvements of 16.87% and 5.46% have been registered over large 2D benchmarks and meta-heuristic approaches, respectively.
In this paper, a synthesis method is proposed based on vector transformation for linear nearest neighbor quantum circuits.Its aim is to construct a linear nearest neighbor quantum circuit, and to reduce the quantum cost of the linear reversible circuit.The vector representation of the sequence of the circuit lines and qubits of quantum gate is given in this method.It realizes the nearest neighbor of the quantum circuit by moving the position of the qubits vector elements, and it does not cause confusion due to comparison and transformation of two vector elements in the circuit.The number of SWAP gates needed to make the quantum circuit nearest neighbors is given, and its correctness is proven.Compared with the current quantum circuit synthesis algorithms, the average optimization rate of the quantum cost is 39.69% for typical benchmark circuits.The algorithm can be applied to all quantum circuits of 2-qubit quantum gates, and can be used in large quantum circuits.
With the advancement of technological footprints, high-end computation techniques, like quantum computation, have made significant progress in the design industry. Although quantum computation has proved itself as the next-generation computing paradigm, it is facing several design challenges, and one such design issue is in the form of the Nearest Neighbour (NN)t. This much-talked NN property demands the qubits in operating quantum gates to be adjacent, and a circuit should satisfy this NN property to be eligible for implementation. Considering the importance of NN enforcement in implementing circuits, we introduce a synthesis approach for the efficient transformation of reversible circuits to equivalent LNN representations. Our main focus in this work is to minimize the use of SWAP gates in designing NN-satisfied MCT-based reversible circuits. Towards transforming input circuits to LNN architecture, we have exploited a template matching scheme followed by two-qubit reordering policies, global and local, to improve the NN designs and reduce SWAP utilization. In finding the global solution, here we have used a dynamic programming algorithm where the initial order of qubit lines gets changed, while a heuristic-based SWAP placement function is used for finding a local qubit order sequence. The proposed synthesis workflow has been tested over an extensive set of benchmark functions, and comparison with the reported design approaches showed a substantial reduction in cost parameters.
In the last couple of years, quantum computing has come out as emerging trends of computation not only due to its immense popularity but also for its commitment towards physical realization of quantum circuit in on-chip units. At the same time, the process of physical realization has faced several design constraints and one such problem is nearest neighbor (NN) enforcement which demands all the operating qubits to be placed adjacent in the implementable circuit. Though SWAP gate embedment can transform a design into NN architecture, it still creates overhead in the design. So, designing algorithms to restrict the use of SWAPs bears high importance. Considering this fact, in this work, we are proposing a heuristic-based improved qubit placement strategy for efficient implementation of NN circuit. Two different design policies are being developed here. In the first scheme, a global reordering technique based on clustering approach is shown. In the second scheme, a local reordering technique based on look-ahead policy is developed. This look-ahead strategy considers the impact over the gates in the circuit and thereby estimates the effect using a cost metric to decide the suitable option for SWAP implementation. Furthermore, the joint use of both the ordering schemes also has been explored here. To ascertain the correctness of our design algorithms, we have tested them over a wide range of benchmarks and the obtained results are compared with some state-of-the-art design approaches. From this comparison, we have witnessed a considerable reduction on SWAP cost in our design scheme against the reported works’ results.
Linear Nearest Neighbor (LNN) synthesis in reversible circuits has emerged as an important issue in terms of technological implementation for quantum computation. The objective is to obtain a LNN architecture with minimum gate cost. As achieving optimal synthesis is a hard problem, heuristic methods have been proposed in recent literature. In this work we present a graph partitioning based approach for LNN synthesis with reduction in circuit cost. In particular, the number of SWAP gates required to convert a given gate-level quantum circuit to its equivalent LNN configuration is minimized. Our algorithm determines the reordering of indices of the qubit line(s) for both single control and multiple controlled gates. Experimental results for placing the target qubits of Multiple Controlled Toffoli (MCT) library of benchmark circuits show a significant reduction in gate count and quantum gate cost compared to those of related research works.