Perspective: Quantum Thermodynamics

Classical thermodynamics is unrivalled in its range of applications and relevance to everyday life. It enables a description of complex systems, made up of microscopic particles, in terms of a small number of macroscopic quantities, such as work and entropy. As systems get ever smaller, fluctuations of these quantities become increasingly relevant, prompting the development of stochastic thermodynamics. Recently we have seen a surge of interest in exploring the quantum regime, where the origin of fluctuations is quantum rather than thermal. Many questions, such as the role of entanglement and the emergence of thermalisation, lie wide open. Answering these questions may lead to the development of quantum heat engines and refrigerators, as well as to vitally needed simple descriptions of quantum many-body systems.Comment: 7 pages, comments very welcome

A cold strontium Rydberg gas

Cold gases of Rydberg atoms are an ideal system in which to study the novel effects of strong interatomic interactions. This thesis describes the design and construction of the world's first experiment to study Rydberg states in a cold gas of an alkaline earth metal, in this particular case strontium. We have studied a wide range of Rydberg states, and have developed a sensitive ``step-scan" spectroscopic technique that detects the spontaneous ionization of the Rydberg gas. The step-scan method is used to acquire Stark maps, and these measurements verify a single-electron model for calculating dipole matrix-elements. From the matrix-elements, interaction strengths between strontium Rydberg atoms have been calculated for the first time. The presence of two valence electrons in an alkaline earth metal, such as strontium, offers a new angle on the study of Rydberg atoms. We create doubly excited ``autoionizing" states, the first such study in a cold gas. Autoionization is used as a high yield probe of Rydberg states, and enables a study of excitation dynamics with nanosecond time-resolution. We show that autoionization can quantitatively identify and elucidate state mixing in the Rydberg gas, and probe population transfer at the very onset of ultra-cold plasma formation

Simultaneous cooling of coupled mechanical oscillators using whispering gallery mode resonances

We demonstrate simultaneous center-of-mass cooling of two coupled oscillators, consisting of a microsphere-cantilever and a tapered optical fiber. Excitation of a whispering gallery mode (WGM) of the microsphere, via the evanescent field of the taper, provides a transduction signal that continuously monitors the relative motion between these two microgram objects with a sensitivity of 3 pm. The cavity enhanced optical dipole force is used to provide feedback damping on the motion of the micron-diameter taper, whereas a piezo stack is used to damp the motion of the much larger (up to $180\,\mu$m in diameter), heavier (up to $1.5\times 10^{-7}\,$kg) and stiffer microsphere-cantilever. In each feedback scheme multiple mechanical modes of each oscillator can be cooled, and mode temperatures below 10 K are reached for the dominant mode, consistent with limits determined by the measurement noise of our system. This represents stabilization on the picometer level and is the first demonstration of using WGM resonances to cool the mechanical modes of both the WGM resonator and its coupling waveguide.Comment: 10 pages, 8 figure

Factors Affecting the Implementation And Use of Technology in Teaching Biology Courses in Florida's Community Colleges

Students are constantly immersed in Hollywood glitz, MTV music videos and fastpaced television commercials. For "better or for worse" the movement to make communication a multimedia presentation is upon us. Educational technology -multimedia/Internet - is playing an increasingly important role as a teaching and learning supplement in modern classrooms and has been suggested as an avenue to improve science education. Potential benefits of the Internet, CD-ROMS, Videodiscs, WebCT, course web sites and other computer-based resources include increased communication among students and between instructor and students. Recently, although not a new idea for some, it has been demonstrated that for a significant number of students, learning occurs more readily if the material is presented visually as compared to verbally. Visual presentation is what multimedia is all about. Biology in particular seems to benefit from the application of technology in the classroom since rapid advances in the field make it nearly impossible for textbooks to remain current. Many biology instructors are seeking to take advantage of these benefits by using technology as an increasingly integral part of the teaching experience. This research involves an investigation into how multimedia and the Internet are or are not being used in the teaching of biology courses at the community college level in the State of Florida. A questionnaire was developed to elicit biology faculty perceptions of factors that encourage and those that inhibit their use of the Internet and multimedia in the classroom and in the laboratory.The Educational Technology Survey was designed for ease of response in order to encourage a high return, and respondents answered the survey via the Internet. The collected data were analyzed by using distributions of frequencies and percentages. Perhaps the most outstanding feature noticeable as a result of this research is that instructor interest was the number one factor responsible for instructors using the Internet or any other form of multimedia. Without the resources, time, faculty development, and technical support, teachers are less likely to use technology in their laboratory and classroom presentations. Educational technology offers exciting possibilities to advance and change teaching, and this research points out some of the factors affecting the implementation of such technology. The study concludes with recommendations for faculty as well as administrators in their efforts to implement technology into the curriculum. Also included are suggestions for further research

The rise of the quantum machines

Technological devices are getting ever smaller, but as they approach the scale at which quantum physics matters, our understanding of how they interact with their environment evaporates. The authors of this article explain how a better understanding of quantum thermodynamics could kick-start a new industrial revolution on the tiniest scale.peer-reviewe

Quantum cooling and squeezing of a levitating nanosphere via time-continuous measurements

With the purpose of controlling the steady state of a dielectric nanosphere levitated within an optical cavity, we study its conditional dynamics under simultaneous sideband cooling and additional time-continuous measurement of either the output cavity mode or the nanosphere's position. We find that the average phonon number, purity and quantum squeezing of the steady-states can all be made more non-classical through the addition of time-continuous measurement. We predict that the continuous monitoring of the system, together with Markovian feedback, allows one to stabilize the dynamics for any value of the laser frequency driving the cavity. By considering state-of-the-art values of the experimental parameters, we prove that one can in principle obtain a non-classical (squeezed) steady-state with an average phonon number $n_{\sf ph}\approx 0.5$.Comment: 10 pages, 9 figures; v2: close to published versio

Levitated electromechanics: all-electrical cooling of charged nano- and micro-particles

We show how charged levitated nano- and micro-particles can be cooled by interfacing them with an $RLC$ circuit. All-electrical levitation and cooling is applicable to a wide range of particle sizes and materials, and will enable state-of-the-art force sensing within an electrically networked system. Exploring the cooling limits in the presence of realistic noise we find that the quantum regime of particle motion can be reached in cryogenic environments both for passive resistive cooling and for an active feedback scheme, paving the way to levitated quantum electromechanics.Comment: Manuscript: 16 pages, 5 figures. Supplementary material: 3 pages 2 figure

Optically driven ultra-stable nanomechanical rotor

Nanomechanical devices have attracted the interest of a growing interdisciplinary research community, since they can be used as highly sensitive transducers for various physical quantities. Exquisite control over these systems facilitates experiments on the foundations of physics. Here, we demonstrate that an optically trapped silicon nanorod, set into rotation at MHz frequencies, can be locked to an external clock, transducing the properties of the time standard to the rod's motion with the remarkable frequency stability $f_{\rm r}/\Delta f_{\rm r}$ of $7.7 \times 10^{11}$. While the dynamics of this periodically driven rotor generally can be chaotic, we derive and verify that stable limit cycles exist over a surprisingly wide parameter range. This robustness should enable, in principle, measurements of external torques with sensitivities better than 0.25zNm, even at room temperature. We show that in a dilute gas, real-time phase measurements on the locked nanorod transduce pressure values with a sensitivity of 0.3%.Comment: 5 pages, 4 figure