Gravitational wave detection beyond the standard quantum limit using a negative-mass spin system and virtual rigidity

Abstract

Gravitational wave detectors (GWDs), which have brought about a new era in astronomy, have reached such a level of maturity that further improvement necessitates quantum-noise-evading techniques. Numerous proposals to this end have been discussed in the literature, e.g., invoking frequency-dependent squeezing or replacing the current Michelson interferometer topology by that of the quantum speedmeter. Recently, a proposal based on the linking of a standard interferometer to a negative-mass spin system via entangled light has offered an unintrusive and small-scale new approach to quantum noise evasion in GWDs [Phys. Rev. Lett. 121, 031101 (2018)]. The solution proposed therein does not require modifications to the highly refined core optics of the present GWD design and, when compared to previous proposals, is less prone to losses and imperfections of the interferometer. In the present article, we refine this scheme to an extent that the requirements on the auxiliary spin system are feasible with state-of-the-art implementations. This is accomplished by matching the effective (rather than intrinsic) susceptibilities of the interferometer and spin system using the virtual rigidity concept, which, in terms of implementation, requires only suitable choices of the various homodyne, probe, and squeezing phases.

Emaranhamento multicor para conexão de sistemas quânticos

“…Polzik and Khalili proposed to enhance the sensitivity of gravitational wave detectors beyond the SQL by measuring the signal in relation to a negative mass reference frame [1,28]. Calculations show that broadband sensitivity improvement can be achieved with current technology.…”

“…The focus is on the low-frequency regime because it is the target frequency of gravitational wave detectors where the source is going to be applied. We do not try to describe how the source is going to be used in the original proposal [1,28]. We start the chapter by presenting the laser sources used in the experiment, their amplitude noise, and overall stability.…”

“…We developed a NOPO focusing on two-color entanglement in the audio frequency range. Our goal is to provide the quantum channel necessary to connect Cs atoms and GWD as part of the back action cancellation scheme proposed in [1,28]. This chapter describes this part of the project, as it was developed in the Niels Bohr Institute.…”

“…The proposal [1,28] needs at least two lasers as initial sources: the 1064 nm laser that operates at the GWD interferometer light and the 852 nm laser that allows the light to interact with Cs atoms. Careful characterization of the noise in each laser is fundamental to determine the frequency limit where entanglement can be measured.…”

Towards the teleportation between rubidium atoms and light in the telecom C-band

“…To achieve this purpose, we took part on a project to develop an atomic system to be used as a negative mass reference frame in an experiment to overcome the standard quantum limit in gravitational wave detectors through backaction cancellation (Khalili and Polzik, 2018;Zeuthen et al, 2019). This project was implemented at the Niels Bohr Institute under the supervision of professor Eugene Polzik.…”