Optical cavity

About: Optical cavity is a research topic. Over the lifetime, 17025 publications have been published within this topic receiving 273582 citations. The topic is also known as: optical resonator & resonating cavity.

Self-cooling of a micromirror by radiation pressure

Abstract: Cooling of mechanical resonators is currently a popular topic in many fields of physics including ultra-high precision measurements1, detection of gravitational waves, and the study of the transition between classical and quantum behaviour of a mechanical system. Here we report the observation of self-cooling of a micromirror by radiation pressure inside a high-finesse optical cavity. In essence, changes in intensity in a detuned cavity, as caused by the thermal vibration of the mirror, provide the mechanism for entropy flow from the mirror's oscillatory motion to the low-entropy cavity field. The crucial coupling between radiation and mechanical motion was made possible by producing free-standing micromirrors of low mass (m ≈ 400 ng), high reflectance (more than 99.6%) and high mechanical quality (Q ≈ 10,000). We observe cooling of the mechanical oscillator by a factor of more than 30; that is, from room temperature to below 10 K. In addition to purely photothermal effects we identify radiation pressure as a relevant mechanism responsible for the cooling. In contrast with earlier experiments, our technique does not need any active feedback. We expect that improvements of our method will permit cooling ratios beyond 1,000 and will thus possibly enable cooling all the way down to the quantum mechanical ground state of the micromirror.

On-chip optical isolation in monolithically integrated non-reciprocal optical resonators

Abstract: Scientists report the fabrication of a nonreciprocal optical resonator with a small length footprint of 290 µm on a silicon-on-insulator substrate. The device achieves unidirectional optical transmission with an isolation ratio of up to 19.5 dB near the telecommunications wavelength of 1,550 nm in a homogeneous external magnetic field.

Scalable photonic quantum computation through cavity-assisted interactions.

Abstract: We propose a scheme for scalable photonic quantum computation based on cavity-assisted interaction between single-photon pulses. The prototypical quantum controlled phase-flip gate between the single-photon pulses is achieved by successively reflecting them from an optical cavity with a single-trapped atom. Our proposed protocol is shown to be robust to practical noise and experimental imperfections in current cavity-QED setups.

Quantum-coherent coupling of a mechanical oscillator to an optical cavity mode

Abstract: Demonstration of an optomechanical system that works as a quantum interface between light and micro-mechanical motion. The possibility of controlling the quantum states of micro- and nanomechanical oscillators has been of great interest in recent years. Although various mechanical resonators have been cooled to their quantum ground state, there are few reports of experiments in which this quantum regime is further explored and used, for example, to exchange quantum information. Previously, quantum coupling between mechanical degrees of freedom and microwave radiation has been shown. Now, Verhagen et al. demonstrate an optomechanical system, cooled by radiation pressure, that works as a quantum interface between a mechanical oscillator and optical photons, offering the advantage that standard optical fibres can be used to extract the quantum information. Optical laser fields have been widely used to achieve quantum control over the motional and internal degrees of freedom of atoms and ions1,2, molecules and atomic gases. A route to controlling the quantum states of macroscopic mechanical oscillators in a similar fashion is to exploit the parametric coupling between optical and mechanical degrees of freedom through radiation pressure in suitably engineered optical cavities3,4,5,6. If the optomechanical coupling is ‘quantum coherent’—that is, if the coherent coupling rate exceeds both the optical and the mechanical decoherence rate—quantum states are transferred from the optical field to the mechanical oscillator and vice versa. This transfer allows control of the mechanical oscillator state using the wide range of available quantum optical techniques. So far, however, quantum-coherent coupling of micromechanical oscillators has only been achieved using microwave fields at millikelvin temperatures7,8. Optical experiments have not attained this regime owing to the large mechanical decoherence rates9 and the difficulty of overcoming optical dissipation10. Here we achieve quantum-coherent coupling between optical photons and a micromechanical oscillator. Simultaneously, coupling to the cold photon bath cools the mechanical oscillator to an average occupancy of 1.7 ± 0.1 motional quanta. Excitation with weak classical light pulses reveals the exchange of energy between the optical light field and the micromechanical oscillator in the time domain at the level of less than one quantum on average. This optomechanical system establishes an efficient quantum interface between mechanical oscillators and optical photons, which can provide decoherence-free transport of quantum states through optical fibres. Our results offer a route towards the use of mechanical oscillators as quantum transducers or in microwave-to-optical quantum links11,12,13,14,15.

Generation of ultrastable microwaves via optical frequency division

Abstract: Researchers demonstrate a microwave generator based on a high-Q optical resonator and a frequency comb functioning as an optical-to-microwave divider. They generate 10 GHz electrical signals with a fractional frequency instability of ≤8 × 10−16 at 1 s.