Interference of clocks: A quantum twin paradox.

Loriani, Sina; Friedrich, Alexander; Ufrecht, Christian; Di Pumpo, Fabio; Kleinert, Stephan; Abend, Sven; Gaaloul, Naceur; Meiners, Christian et al. · Sci Adv · 2019

basic_science · Level V

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Abstract

The phase of matter waves depends on proper time and is therefore susceptible to special-relativistic (kinematic) and gravitational (redshift) time dilation. Hence, it is conceivable that atom interferometers measure general-relativistic time-dilation effects. In contrast to this intuition, we show that (i) closed light-pulse interferometers without clock transitions during the pulse sequence are not sensitive to gravitational time dilation in a linear potential. (ii) They can constitute a quantum version of the special-relativistic twin paradox. (iii) Our proposed experimental geometry for a quantum-clock interferometer isolates this effect.