arXiv subjects

Albert Schliesser

Publications and source records attributed to Albert Schliesser.

46 records · Page 3Linked to original sources

arXiv2012

Electromechanically induced absorption in a circuit nano-electromechanical system

A detailed analysis of electromechanically induced absorption (EMIA) in a circuit nano-electromechanical hybrid system consisting of a superconducting microwave resonator coupled to a nanomechanical beam is presented. By performing two-tone spectroscopy experiments we have studied EMIA as a function of the drive power over a wide range of drive and probe tone detunings. We find good quantitative agreement between experiment and theoretical modeling based on the Hamiltonian formulation of a generic electromechanical system. We show that the absorption of microwave signals in an extremely narrow frequency band (Δω/2π<5 Hz) around the cavity resonance of about 6 GHz can be adjusted over a range of more than 25 dB on varying the drive tone power by a factor of two. Possible applications of this phenomenon include notch filters to cut out extremely narrow frequency bands (< Hz) of a much broader band of the order of MHz defined by the resonance width of the microwave cavity. The amount of absorption as well as the filtered frequency is tunable over the full width of the microwave resonance by adjusting the power and frequency of the drive field. At high drive power we observe parametric microwave amplification with the nanomechanical resonator. Due to the very low loss rate of the nanomechanical beam the drive power range for parametric amplification is narrow, since the beam rapidly starts to perform self-oscillations.

cond-mat.mes-hall↗

arXiv2012

Control of microwave signals using circuit nano-electromechanics

Waveguide resonators are crucial elements in sensitive astrophysical detectors [1] and circuit quantum electrodynamics (cQED) [2]. Coupled to artificial atoms in the form of superconducting qubits [3, 4], they now provide a technologically promising and scalable platform for quantum information processing tasks [2, 5-8]. Coupling these circuits, in situ, to other quantum systems, such as molecules [9, 10], spin ensembles [11, 12], quantum dots [13] or mechanical oscillators [14, 15] has been explored to realize hybrid systems with extended functionality. Here, we couple a superconducting coplanar waveguide resonator to a nano-coshmechanical oscillator, and demonstrate all-microwave field controlled slowing, advancing and switching of microwave signals. This is enabled by utilizing electromechanically induced transparency [16-18], an effect analogous to electromagnetically induced transparency (EIT) in atomic physics [19]. The exquisite temporal control gained over this phenomenon provides a route towards realizing advanced protocols for storage of both classical and quantum microwave signals [20-22], extending the toolbox of control techniques of the microwave field.

cond-mat.mes-hall↗

arXiv2012

Mid-infrared frequency combs

Laser frequency combs are coherent light sources that emit a broad spectrum consisting of discrete, evenly spaced narrow lines, each having an absolute frequency measurable within the accuracy of an atomic clock. Their development, a decade ago, in the near-infrared and visible domains has revolutionized frequency metrology with numerous windfalls into other fields such as astronomy or attosecond science. Extension of frequency comb techniques to the mid-infrared spectral region is now under exploration. Versatile mid-infrared frequency comb generators, based on novel laser gain media, nonlinear frequency conversion or microresonators, promise to significantly expand the tree of applications of frequency combs. In particular, novel approaches to molecular spectroscopy in the fingerprint region, with dramatically improved precision, sensitivity, recording time and/or spectral bandwidth may spark off new discoveries in the various fields relevant to molecular sciences.

physics.optics↗

arXiv2011

Phase noise measurement of external cavity diode lasers and implications for optomechanical sideband cooling of GHz mechanical modes

Cavity opto-mechanical cooling via radiation pressure dynamical backaction enables ground state cooling of mechanical oscillators, provided the laser exhibits sufficiently low phase noise. Here, we investigate and measure the excess phase noise of widely tunable external cavity diode lasers, which have been used in a range of recent nano-optomechanical experiments, including ground-state cooling. We report significant excess frequency noise, with peak values on the order of 10^7 rad^2 Hz near 3.5 GHz, attributed to the diode lasers' relaxation oscillations. The measurements reveal that even at GHz frequencies diode lasers do not exhibit quantum limited performance. The associated excess backaction can preclude ground-state cooling even in state-of-the-art nano-optomechanical systems.

quant-ph↗

arXiv2010

Optomechanical sideband cooling of a micromechanical oscillator close to the quantum ground state

Cooling a mesoscopic mechanical oscillator to its quantum ground state is elementary for the preparation and control of low entropy quantum states of large scale objects. Here, we pre-cool a 70-MHz micromechanical silica oscillator to an occupancy below 200 quanta by thermalizing it with a 600-mK cold 3He gas. Two-level system induced damping via structural defect states is shown to be strongly reduced, and simultaneously serves as novel thermometry method to independently quantify excess heating due to the cooling laser. We demonstrate that dynamical backaction sideband cooling can reduce the average occupancy to 9+-1 quanta, implying that the mechanical oscillator can be found (10+- 1)% of the time in its quantum ground state.

quant-ph↗

arXiv2010

Determination of the vacuum optomechanical coupling rate using frequency noise calibration

The strength of optomechanical interactions in a cavity optomechanical system can be quantified by a vacuum coupling rate $\vcr$ analogous to cavity quantum electrodynamics. This single figure of merit removes the ambiguity in the frequently quoted coupling parameter defining the frequency shift for a given mechanical displacement, and the effective mass of the mechanical mode. Here we demonstrate and verify a straightforward experimental technique to derive the vacuum optomechanical coupling rate. It only requires applying a known frequency modulation of the employed electromagnetic probe field and knowledge of the mechanical oscillator's occupation. The method is experimentally verified for a micromechanical mode in a toroidal whispering-gallery-resonator and a nanomechanical oscillator coupled to a toroidal cavity via its near field.

quant-ph↗

arXiv2010

Cavity optomechanics with whispering-gallery-mode optical micro-resonators

Parametric coupling of optical and mechanical degrees of freedom forms the basis of many ultra-sensitive measurements of both force and mechanical displacement. An optical cavity with a mechanically compliant boundary enhances the optomechanical interaction, but also gives rise to qualitatively new coupled dynamics. As early as 1967, in a pioneering work, V. Braginsky analyzed theoretically the role of radiation pressure in the interferometric measurement process, but it has remained experimentally unexplored for many decades. Here, we use whispering-gallery-mode (WGM) optical microresonators to study these radiation pressure phenomena. Optical microresonators simultaneously host optical and mechanical modes, which are systematically analyzed and optimized to feature ultra-low mechanical dissipation, photon storage times exceeding the mechanical oscillation period (i.e. the "resolved-sideband regime") and large optomechanical coupling. It is demonstrated that dynamical backaction can be employed to cool mechanical modes, i.e., to reduce their thermally excited random motion. Utilizing this novel technique together with cryogenic pre-cooling of the mechanical oscillator, the phonon occupation of mechanical radial-breathing modes could be reduced to about 60 excitation quanta. The corresponding displacement fluctuations are monitored interferometrically with a sensitivity at the level of 10^-18 m/Hz^(1/2), which is below the imprecision at the standard quantum limit (SQL). It is shown that optical measurement techniques employed here are operating in a near-ideal manner according to the principles of quantum measurement, displaying a backaction-imprecision product close to the quantum limit. An outlook on optomechanical experiments with crystalline WGM resonators and the effect of "optomechanically induced transparency" (analogous to electromagnetically induced transparency) is given.

quant-ph↗

arXiv2009

Cryogenic properties of optomechanical silica microcavities

We present the optical and mechanical properties of high-Q fused silica microtoroidal resonators at cryogenic temperatures (down to 1.6 K). A thermally induced optical multistability is observed and theoretically described; it serves to characterize quantitatively the static heating induced by light absorption. Moreover the influence of structural defect states in glass on the toroid mechanical properties is observed and the resulting implications of cavity optomechanical systems on the study of mechanical dissipation discussed.

quant-ph↗

arXiv2007

Cavity Enhanced Optical Vernier Spectroscopy, Broad Band, High Resolution, High Sensitivity

A femtosecond frequency comb provides a vast number of equidistantly spaced narrow band laser modes that can be simultaneously tuned and frequency calibrated with 15 digits accuracy. Our Vernier spectrometer utilizes all of theses modes in a massively parallel manner to rapidly record both absorption and dispersion spectra with a sensitivity that is provided by a high finesse broad band optical resonator and a resolution that is only limited by the frequency comb line width while keeping the required setup simple.

physics.optics↗

arXiv2005

Wide-field prime-focus Imaging Atmospheric Cherenkov Telescopes: A systematic study

By means of third-order optical theory as well as ray-tracing simulations we have investigated the feasibility of wide-field imaging atmospheric Cherenkov telescopes with a reflective prime-focus design. For a range of desired optical resolutions, we have determined the largest available field-of-view of single-piece spherical, single-piece parabolic, tessellated spherical, tessellated parabolic and Davies-Cotton designs, always considering a wide range of design parameters. The Davies-Cotton design exhibits a surprising similarity to the tessellated parabolic design in its qualitative behaviour. Also, elliptic telescope designs with better off-axis imaging properties than Davies-Cotton are presented. We show that by using f/2 optics it is possible to build prime-focus telescopes with a full field-of-view of 10 degree at 0.1 degree resolution.

astro-ph↗