A very long-lived atomic state

Thad Gilbert Walker

Wei Qin, Adam Miranowicz, Hui Jing +1 more

We propose to create and stabilize long-lived macroscopic quantum superposition states in atomic ensembles. We show that using a fully quantum parametric amplifier can cause the simultaneous decay of two atoms and, in turn, create stabilized atomic Schr\"{o}dinger cat states. Remarkably, even with modest parameters these intracavity atomic cat states can have an extremely long lifetime, up to \emph{4 orders of magnitude} longer than that of intracavity photonic cat states under the same parameter conditions, reaching \emph{tens of milliseconds}. This lifetime of atomic cat states is ultimately limited to \emph{several seconds} by extremely weak spin relaxation and thermal noise. Our work opens up a new way toward the long-standing goal of generating large-size and long-lived cat states, with immediate interests both in fundamental studies and noise-immune quantum technologies.

Wei Qin, Adam Miranowicz, Hui Jing +1 more

We propose to create and stabilize long-lived macroscopic quantum superposition states in atomic ensembles. We show that using a fully quantum parametric amplifier can cause the simultaneous decay of two atoms, and in turn create stabilized atomic Schr\{o}dinger cat states. Remarkably, even with modest parameters these atomic cat states can have an extremely long lifetime, up to \emph{four orders of magnitude} longer than that of intracavity photonic cat states under the same parameter conditions, reaching \emph{tens of milliseconds}. This lifetime of atomic cat states is ultimately limited to \emph{several seconds} by extremely weak spin relaxation and thermal noise. Our work opens up a new way towards the long-standing goal of engineering large-size and long-lived cat states, with immediate interests both in fundamental studies and noise-immune quantum information processing.

(The AEgIS collaboration)

The 33P state of positronium is an intermediate level suitable for producing long-lived positronium states. On one hand, it can be used in a two-step laser excitation scheme from the ground state to Rydberg levels. On the other hand, excitation of positronium to 33P level is a simple pathway for producing metastable 23S positronium atoms by spontaneous radiactive decay. In this work, experiments showing the production of such long-lived levels, using the 33P state as intermediate state, are presented. The characteristics of the two long-lived levels, in view of experiments of deflectometry/interferometry with positronium, are discussed.

Hartmut Häffner, Ferdinand Schmidt‐Kaler, W. Hänsel +10 more