Superconducting Quantum Diodes Without Refrigeration and Computing Applications

Quantum computing is a potential solution to the limitations of current computing devices, but the need for superconductivity has led to prohibitively high operational costs and energy consumption. A major bottleneck is the low critical temperature needed to achieve superconductivity. Here, a quantum diode system is proposed that utilizes a circuit approach to achieve superconductivity at room temperature. Two opposed p–n diodes are connected to another junction in one of two configurations (A and B systems) that cancels the electric field in the depletion layer of each diode, which causes electrons and holes to reappear and prevents their recombination. Thus, the combination energy of a Cooper pair (i.e., exciton) is very strong, and Bose–Einstein condensation is maintained even at room temperature. When a bias voltage is applied between the A and B systems, Lorentz conservation imparts momentum (i.e., wavenumber) to the carriers in the absence of any internal voltage, so a superconducting bias current density appears without any need for cooling. Numerical calculations including many-body interactions revealed that constant phases for the macroscopic wavefunctions of p- and n-type semiconductors converged, which confirmed that Bose–Einstein condensation and the Meissner effect occurred. Moreover, the quantum diode system exhibited rectification characteristics and a switching speed on the order of 10⁻¹⁴ s. These switching properties and large superconducting bias current were used to develop NOT and NAND gates with direct quantum correlations that are unaffected by random and thermal noise.