Quantum algorithm and experimental demonstration for the subset sum problem

Abstract

To solve the subset sum problem, a well-known nondeterministic polynomial-time complete problem that is widely used in encryption and resource scheduling, we propose a feasible quantum algorithm that utilizes fewer qubits to encode and achieves quadratic speedup. Specifically, this algorithm combines an amplitude amplification algorithm with quantum phase estimation, and requires n + t + 1 qubits and O(2 (0.5+o(1))n ) operations to obtain the solution, where n is the number of elements, and t is the number of qubits used to store the eigenvalues. To verify the performance of the algorithm, we simulate the algorithm with the online quantum simulator of IBM named ibmq simulator using Qiskit and then run it on two IBM quantum computers called ibmq santiago and ibmq bogota. The experimental results indicate that compared with the brute force algorithm, the proposed algorithm results in quadratic acceleration for the problem of a set S with four elements and two subsets whose sum equals target w. Using the iterator twice, we obtain success probabilities of 0.940 ± 0.004, 0.751 ± 0.040, and 0.665 ± 0.060 on the simulator, ibmq santiago, and ibmq bogota, respectively, and the fidelity between the theoretical and experimental quantum states is calculated to be 0.944 ± 0.002, 0.753 ± 0.017, and 0.657 ± 0.028, respectively. If the error rates of the experimental quantum logic gates can be reduced, the success probabilities of the proposed algorithm on real quantum devices can be further improved.

Secure nano-communication framework using RSCV cryptographic circuit in IBM Q

“…The simulation results in IBM simulator and classical system in [24] demonstrate the effectiveness of the suggested quantum picture encryption method. To resolve the popular unpredictable polynomial-time complete issue known as the subset sum, an effective algorithm with fewer qubits is proposed in [25] which obtains quadratic acceleration and experimented with in two IBM Q online simulators (ibmq_bogota and ibmq_santigo). An algorithm is shown in [26] to demonstrate homomorphic encryption.…”