Long-lived Macroscopic Schrödinger Cat States in Atomic Ensembles

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.

M. Kira, S. W. Koch, Ryan P. Smith +2 more

David Vitali

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.

Eugene Simon Polzik, Brian Julsgaard, Jens Lykke Sørensen +1 more

Summary form only given. A new approach to the problem of the quantum interface between light and atoms has been recently developed. The method utilizes free space dispersive interaction between pulses of light and spin polarized atomic ensembles. Entanglement between the polarization state of light and the collective spin state of atoms is established by measurement, more precisely by detection of light in a certain polarization basis. In the first demonstration of this approach we have generated a long-lived entangled state of two separate macroscopic atomic samples by a polarization measurement on light transmitted through the samples. We then have shown that this approach also works for mapping of a quantum state of light onto long-lived atomic spin state paving the road towards realization of the quantum memory for light. Recently we have also extended the free space light-atoms interface beyond the continuous variables in the proposal, where a coherent superposition "cat" state of an atomic ensemble is generated by a measurement sequence. Progress with other communication protocols such as atomic state teleportation and multiparty networks will be presented.

Octavio Castaños, Ramón López–Peña, Vladimir I. Man’ko