Quantum Logic Gates Based on DNAtronics, RNAtronics, and Proteintronics

Abstract

A quantum computer (QC) [1][2][3] implements quantum bits (qubits) and qudits [4] (e.g., qutrits [5] and ququarts [6] ) to conduct computations instead of a traditional digital computer built from a transistor in which a binary bit is represented by either 1 or 0. Based on the Church-Turing-Deutch principle, a computing machine conducts simulations of every physical process and behaves as a universal QC. [7][8][9] Unlike a classical bit, the basic unit of a qubit is the superposition c 0 j0i þ c 1 j1i of two qubit states, j0i and j1i, where c 0 and c 1 denote complex numbers. [10] However, the operation of a QC with a relatively large number of qubits for conducting universal computations has attracted considerable attention. [11] Using quantum algorithms such as Shor's algorithm, [12] a quantum many-body simulation [10] and Simon's algorithm, [13] a large-scale QC could tackle problems faster than a classical computer. Until now, present quantum algorithms have been implemented by superconducting flux qubits (D-wave systems), [14] nuclear magnetic resonance (NMR) techniques, [15,16] photonic QCs, [17] and ion-trap systems. [18,19] For NMR techniques, Shor's factorizing algorithm, [20] which uses seven qubits, has been applied. The qubits are encoded in mixed states, and the output is a result of an ensemble measurement. Hence, NMR QCs are not scalable. [21] For a trapped-ion QC, the qubits are stored in the electronic states of ions and are controllable in long-lived internal states, and their quantum states can be detected with a very high efficiency close to 100%. [19,22,23] These characteristics permit the manipulation of pure states to build a scalable and universal QC. [24] Nevertheless, no quantum logic gate has been executed with a subnano-scaled molecular transistor to date.Classical computers operate with a microprocessor that consists of semiconductor logic gates with electronic input and output signals of a binary digital nature. The output can be only one of the two states, on or off, corresponding to logic 1 or 0, respectively. Consequently, the signal pattern can be described by a truth table based on Boolean algebra. [25] This critical feature in constructing computers could be conducted by a single-molecule transistor as a future classical computer. [26,27] However, accomplishing concerted arrays of molecular transistors remains an intrinsic challenge. [28,29] Recently, several experiments have shown the feasibility of conducting computations at the molecular level. For example, DNA is a reliable biomolecule and can be used to build molecular computation systems; however, it was used as a classical liquid computer to solve the Hamiltonian path problem. [30] DNA-based logic gates [25,31] have been designed by deoxyribozyme ligases. [32,33] It is possible to integrate the logic gates into simple circuits using a series of deoxyribozyme ligases communicating via a deoxyribozyme phosphodiesterase. [28] Meanwhile, NOT and two-input AND gates were integrated into an INHIBIT logic gate, and signal trans...

SARS-CoV-2 spike and ACE2 entanglement-like binding

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