Transmitting a signal in negative time

Abstract

There is no self-adjoint time operator defined in quantum mechanics. However, time intervals can be defined in several ways and can also be probed experimentally. Our interest in this work is traversal time and signal propagation time. According to Copenhagen interpretation of quantum mechanics, the two should be the same but the issue is not settled yet in regimes where they can be negative. We use Argand-diagram and Burgers-circuit to show that the correct traversal time and the correct signal propagation time can be identically negative implying signal can be propagated in negative time. Some other physical consequences are discussed.