Physical Review Letters

Anomalous Tunneling of Phonon Excitations between Two Bose-Einstein Condensates

Yu. Kagan, Dmitry L. Kovrizhin, Leonid A. Maksimov

Published Apr 2, 2003• 47 citations

Abstract

We discuss the tunneling of phonon excitations across a potential barrier separating two condensates. It is shown that a strong barrier proves to be transparent for the excitations at low energy epsilon. Moreover, the transmission is reduced with increasing epsilon in contrast to the standard dependence. This anomalous behavior is due to the existence of a quasiresonance interaction. The origin of this interaction is a result of the formation of a special well determined by the density distribution of the condensate in the vicinity of a high barrier.

DOI: 10.1103/physrevlett.90.130402

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Physical Review Letters

Anomalous Tunneling of Phonon Excitations between Two Bose-Einstein Condensates

Yu. Kagan, Dmitry L. Kovrizhin, Leonid A. Maksimov

Published Apr 2, 2003• 47 citations

Publisher

Abstract

DOI: 10.1103/physrevlett.90.130402

Related papers

The anomalous tunneling of Bose-condensate excitations

Yu. Kagan, Dmitry L. Kovrizhin, Leonid A. Maksimov

We discuss the tunneling of phonon excitations across a potential barrier separating two condensate bulks. It is shown that the strong barrier proves to be transparent for the excitations at low energy $ε$ . Moreover, the transmission is reduced with increasing $ε$ in contrast to the standard dependence. This anomalous behavior is due to an existence of the quasiresonance interaction. The origin of this interaction is a result of the formation of the special well determined by the density distribution of condensate in the vicinity of a high barrier.We discuss the tunneling of phonon excitations across a potential barrier separating two condensate bulks. It is shown that the strong barrier proves to be transparent for the excitations at low energy $ε$. Moreover, the transmission is reduced with increasing $ε$ in contrast to the standard dependence. This anomalous behavior is due to an existence of the quasiresonance interaction. The origin of this interaction is a result of the formation of the special well determined by the density distribution of condensate in the vicinity of a high barrier.

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ε

. Moreover, the transmission is reduced with increasing

ε

in contrast to the standard dependence. This anomalous behavior is due to an existence of the quasiresonance interaction. The origin of this interaction is a result of the formation of the special well determined by the density distribution of condensate in the vicinity of a high barrier.

We investigate tunneling properties of Bogoliubov phonons in a Bose-Einstein condensate. We find the anomalous enhancement of the quasiparticle current

J_{\rm q}

carried by Bogoliubov phonons near a potential barrier, due to the supply of the excess current from the condensate. This effect leads to the increase of quasiparticle transmission probability in the low energy region found by Kovrizhin {\it et al.}. We also show that the quasiparticle current twists the phase of the condensate wavefunction across the barrier, leading to a finite Josephson supercurrent

J_{\rm s}

through the barrier. This induced supercurrent flows in the opposite direction to the quasiparticle current so as to cancel out the enhancement of

J_{\rm q}

and conserve the total current

J=J_{\rm q}+J_{\rm s}

(u,v)

of low-energy Bogoliubov phonon has the same form as the condensate wave function in the supercurrent state. As a result, the currents

{J}_{u}

and

{J}_{v}

associated with

u

and

v

, respectively, have the same tunneling properties as those of supercurrent carried by condensate. Thus, the tunneling of low-energy Bogoliubov phonon described by the tunneling of these two currents shows perfect transmission. We also show that the supercurrent behaviors of Bogoliubov phonon still exist in the presence of supercurrent carried by condensate, except in the critical supercurrent state. In the critical current state, the perfect transmission is absent, because

{J}_{u}

{J}_{v}

exceeds their upper limit given by the critical value of the supercurrent associated with the condensate. Our results consistently explain the recently proposed two tunneling phenomena associated with Bogoliubov phonon, namely, the anomalous tunneling effect (perfect transmission in the low-energy limit) and the breakdown of the perfect transmission in the critical supercurrent state.