Josephson-type effect in resonant-tunneling heterostructures

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Abstract
We consider resonant-tunneling penetration through double-well semiconductor heterostructures, which may reveal some quantum-mechanical phenomena at the macroscopic level. The Josephson-type effects in these systems are investigated. We obtain simple expressions for the resonant current under a constant and an alternating bias voltage. It is shown that ac oscillations in the resonant current appearing in the case of a constant bias are exponentially damped. Nevertheless, a dc resonant current behaves similarly to the Josephson supercurrent: it rapidly decreases with bias voltage, but it peaks at the points corresponding to Shapiro steps when an alternating voltage is superimposed. Yet the heights of the peaks show a different dependence on the bias voltage than in the case of a Josephson junction. The possibility of observing the Josephson-type effect at room temperatures is discussed.