Programmable reversible logic is emerging as a prospective logic design style for implementation in modern nanotechnology and quantum computing with minimal impact on circuit heat generation. Recent advances in reversible logic using and quantum computer algorithms allow for improved computer architecture and arithmetic logic unit designs. In this paper, a 2*2 Swap gate which is a reduced implementation in terms of quantum cost and delay to the previous Swap gate is presented. Next, a novel 3*3 programmable UPG gate capable of calculating the fundamental logic calculations is presented and verified, and its advantages over the Toffoli and Peres gates are discussed. The UPG is then implemented in a reduced design for calculating n-bit AND, nbit OR and n-bit ZERO calculations. Then, two 3*3 RMUX gates capable of multiplexing two input values with reduced quantum cost and delay compared to the previously existing Fredkin gate is presented and verified. Next, 4*4 reversible gate is presented and verified which is capable of producing the calculations necessary for two-bit comparisons. The UPG and RC are implemented in the design of novel sequential and tree-based comparators. Then, two novel 4*4 reversible logic gates (MRG and PAOG) are proposed with minimal delay, and may be configured to produce a variety of logical calculations on fixed output lines based on programmable select input lines. A 5*5 structure (MG) is proposed that extends the capabilities of both the MRG and PAOG. The comparator designs are verified and its advantages to previous designs are discussed. Then, reversible implementations of ripple-carry, carry-select and Kogge-Stone carry look-ahead adders are analyzed and compared. Next, implementations of the Kogge-Stone adder with sparsity-4, 8 and 16 were designed, verified and compared. The enhanced sparsity-4 Kogge-Stone adder with ripple-carry adders was selected as the best design, and its implemented in the design of a 32-bit arithmetic logic unit is demonstrated. The proposed ALU design is verified and its advantages over the only existing ALU design are quantitatively analyzed.
Programmable reversible logic is emerging as a prospective logic design style for implementation in modern nanotechnology and quantum computing with minimal impact on circuit heat generation. Recent advances in reversible logic using and quantum computer algorithms allow for improved computer architecture and arithmetic logic unit designs. In this paper, a 22 Swap gate which is a reduced implementation in terms of quantum cost and delay to the previous Swap gate is presented. Next, a novel 33 programmable UPG gate capable of calculating the fundamental logic calculations is presented and verified, and its advantages over the Toffoli and Peres gates are discussed. The UPG is then implemented in a reduced design for calculating n-bit AND, nbit OR and n-bit ZERO calculations. Then, two 33 RMUX gates capable of multiplexing two input values with reduced quantum cost and delay compared to the previously existing Fredkin gate is presented and verified. Next, 44 reversible gate is presented and verified which is capable of producing the calculations necessary for two-bit comparisons. The UPG and RC are implemented in the design of novel sequential and tree-based comparators. Then, two novel 44 reversible logic gates (MRG and PAOG) are proposed with minimal delay, and may be configured to produce a variety of logical calculations on fixed output lines based on programmable select input lines. A 55 structure (MG) is proposed that extends the capabilities of both the MRG and PAOG. The comparator designs are verified and its advantages to previous designs are discussed. Then, reversible implementations of ripple-carry, carry-select and Kogge-Stone carry look-ahead adders are analyzed and compared. Next, implementations of the Kogge-Stone adder with sparsity-4, 8 and 16 were designed, verified and compared. The enhanced sparsity-4 Kogge-Stone adder with ripple-carry adders was selected as the best design, and its implemented in the design of a 32-bit arithmetic logic unit is demonstrated. The proposed ALU design is verified and its advantages over the only existing ALU design are quantitatively analyzed.
This paper presents the design, optimization, and simulation of arithmetic circuits using reversible logic for quantum computing applications. The motivation behind this work is to achieve resource-efficient computation through reduced quantum cost, minimized garbage outputs, and lower ancilla requirements. The methodology involves implementing Half Adders, Full Adders, Multiplexers, and Ripple Carry Adders (RCAs) using Toffoli and Peres gates. The proposed 8-bit RCA achieves a quantum cost of 58 using 24 qubits, 8 garbage outputs, and 6 ancilla inputs—showing a significant improvement over conventional Toffoli-based designs that require higher quantum cost and resources. Simulations were conducted on IBM Qiskit and Google Colab using the Qiskit SDK to validate circuit correctness and scalability. The obtained results demonstrate superior resource efficiency and confirm the feasibility of reversible-logic-based quantum arithmetic as a foundation for scalable quantum arithmetic logic units (ALUs) and processors.
Reversible logic provides a foundation for nextgeneration computing systems, particularly in quantum and emerging nanotechnology-based architectures. Unlike conventional logic, reversible gates preserve information and support backward computation, making them crucial for designing quantum circuits. This paper introduces a reversible Arithmetic and Logic Unit (ALU) that performs eight fundamental operations-AND, OR, NOT, XOR, addition, subtraction, increment, and decrement-using Fredkin, Peres, TR, and modified Fredkin gates. A dedicated control unit manages operation selection, ensuring functional flexibility and circuit efficiency. The proposed design achieves significant improvements by minimizing ancilla inputs, quantum cost and garbage outputs, resulting in a total quantum cost of 71 and contains 16 reversible gates and 14 garbage outputs. The architecture was modeled and verified using Xilinx Vivado HLS and ISE 14.7, and implemented on the Nexys A7 (Artix-7) FPGA platform. Comparative analysis demonstrates better efficiency than existing reversible ALU designs, establishing the proposed circuit as a strong candidate for quantum computing and other advanced computing paradigms.
A reconfigurable 16-bit adder utilizing reversible logic is introduced to enhance both energy efficiency and computational performance. The design integrates Toffoli, Peres, and Haghparast–Navi Gate (HNG) to construct optimized full adder units with lower quantum cost, reduced garbage outputs, and minimal constant inputs. A reversible multiplexer is employed to enable seamless switching between Ripple Carry Adder (RCA) and Carry Lookahead Adder (CLA) configurations. While RCA mode supports power-efficient operation, CLA mode enables faster computation, allowing the circuit to adapt to different processing requirements. Performance evaluation is carried out considering propagation delay, power consumption and hardware utilization. The analysis indicates enhanced efficiency over existing reversible adder designs. Due to its adaptable structure and scalable nature, the architecture is appropriate for reversible computing, quantum systems, and low-power VLSI applications.
In recent years, reversible logic has emerged as a promising technology withapplications spanning low-power CMOS, quantum computing, nanotechnology, andoptical computing. Quantum computing, in particular, relies on reversible logic for itsrealization. The construction of low-power and low-loss computational structures iscrucial for developing arithmetic circuits used in quantum computation, nanotechnology,and other low-power digital circuits. This work presents optimized one-digit BCD addersand carries skip BCD adders using new reversible logic gates. The proposed approachaims to minimize quantum cost and optimize performance compared to existing circuits,focusing on reducing the number of reversible gates used and minimizing garbage outputsproduced. The objective is to design faster BCD adders and provide a foundation forbuilding the decimal Arithmetic Logic Unit (ALU) of a Quantum CPU. The work isimplemented using Hardware Description Language (HDL), with Simulation & Synthesisconducted on Xilinx ISE. The design targets the Xilinx Spartan 3E FPGA device. Thisresearch contributes to the advancement of efficient and high-performance arithmeticcircuits suitable for emerging technologies such as quantum computing andnanotechnology.
Compared to classical computing implementations, reversible arithmetic adders offer a valuable platform for implementing quantum computation models in digital systems and specific applications, such as cryptography and natural language processing. Reversible logic efficiently prevents energy wastage through thermal dissipation. This study presents a comprehensive exploration introducing new carry-select adders (CSLA) based on quantum and reversible logic. Five reversible CSLA designs are proposed and compared, evaluating various criteria, including speed, quantum cost, and area, compared to previously published schemes. These comparative metrics are formulated for arbitrary n-bit size blocks. Each design type is described generically, capable of implementing carry-select adders of any size. As the best outcome, this study proposes an optimized reversible adder circuit that addresses quantum propagation delay, achieving an acceptable trade-off with quantum cost compared to its counterparts. This article reduces calculation delay by 66%, 73%, 82%, and 87% for 16, 32, 64, and 128 bits, respectively, while maintaining a lower quantum cost in all cases.
The quantum and reversible paradigm merges the principles of quantum mechanics and reversible computation to enable information-preserving processing. It supports next-generation computing architectures that provide improved scalability and enhanced computational efficiency. Within these architectures, the decimal adder is a key arithmetic component, particularly for Binary Coded Decimal (BCD) operations widely used in financial and commercial systems. However, most reversible BCD adders focus primarily on quantum and reversible metrics, overlooking the critical influence of delay, which makes balanced optimization a significant challenge. This paper presents two reversible BCD adder designs optimized for both delay and quantum cost. One design integrates the decimal carry-skip technique to improve the overall delay. Using reversible logic gates, the proposed architectures efficiently perform BCD addition and implement the required correction logic while maintaining full reversibility. Evaluation results indicate that the proposed designs surpass existing reversible BCD adders, achieving best-case average improvements of 85.12% in delay and 30.75% in quantum cost. These advancements demonstrate the potential of the proposed adders for integration into future quantum-based arithmetic units and scalable reversible computing systems. Moreover, analysis of real banking transaction data underscores the practical importance of BCD addition and its widespread use in accurate and efficient monetary computations.