systems. Here we experimentally demonstrate the micro-macro entanglement of light. The macro system involves over a hundred million photons, whereas the micro system is at the single-photon level. We show that microscopic quantum fluctuations (in field quadrature measurements) on one side are correlated with macroscopic fluctuations (in the photon number statistics) on the other side. Further, we demonstrate entanglement by bringing the macroscopic state back to the single-photon level and performing full quantum state tomography of the final state. Although Schrödinger's thought experiment was originally intended to convey the absurdity of applying quantum mechanics to macroscopic objects, this experiment and related ones suggest that it may apply on all scales.Schrödinger cat states are notoriously difficult to generate and observe because even the minutest interactions of the system with the environment entangle the two, thereby decohering the superposition. In the optical domain, decoherence is mainly due to losses associated with absorption and spurious reflection at interfaces. However, certain optical states exhibit surprising robustness with respect to such losses, and can be truly macroscopic, yet maintain properties of a quantum superposition.There have been several recent studies aimed at creating micromacro entanglement of light [6][7][8] ref. 6 claimed to have demonstrated micro-macro entanglement involving 10 4 photons on the macro side by starting with a polarization-entangled photon pair and amplifying one of the photons. However, these results were shown to be inconclusive by pointing out that equivalent results could be obtained with a separable state 9 . It was subsequently understood 10 that, although the state of ref. 6 is robust to losses, it is very difficult to detect micro-macro entanglement by means of direct measurements (such as photon counting) on the macroscopic state, because the relevant measurements need to have extremely high resolution. This issue may be resolved by bringing the macroscopic state back to the single-photon level by inverting the amplification operation 11 . The type of amplification considered in the above references was based on optical nonlinearities (squeezing). A significantly simpler approach is to use the phase-space displacement operation to render the state in one or both channels macroscopic 6 . One can start with the delocalized single-photon state
We present a scheme for achieving macroscopic quantum superpositions in optomechanical systems by using single photon postselection and detecting them with nested interferometers. This method relieves many of the challenges associated with previous optical schemes for measuring macroscopic superpositions and only requires the devices to be in the weak coupling regime. It requires only small improvements on currently achievable device parameters and allows the observation of decoherence on a time scale unconstrained by the system's optical decay time. Prospects for observing novel decoherence mechanisms are discussed.
We study the simplest optomechanical system with a focus on the bistable regime. The covariance matrix formalism allows us to study both cooling and entanglement in a unified framework. We identify two key factors governing entanglement; namely, the bistability parameter (i.e., the distance from the end of a stable branch in the bistable regime) and the effective detuning, and we describe the optimum regime where entanglement is greatest. We also show that, in general, entanglement is a nonmonotonic function of optomechanical coupling. This is especially important in understanding the optomechanical entanglement of the second stable branch.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.