Opto-mechanical transducers for long-distance quantum communication

We describe a new scheme to interconvert stationary and photonic qubits which is based on indirect qubit-light interactions mediated by a mechanical resonator. This approach does not rely on the specific optical response of the qubit and thereby enables optical quantum interfaces for a wide range of solid state spin and charge based systems. We discuss the implementation of quantum state transfer protocols between distant nodes of a large scale network and evaluate the effect of the main noise sources on the resulting state transfer fidelities. For the specific examples of electronic spin qubits and superconducting charge qubits we show that high fidelity quantum communication protocols can be implemented under realistic experimental conditions.Comment: Version as accepted by PR

Single-photon Optomechanics

Optomechanics experiments are rapidly approaching the regime where the radiation pressure of a single photon displaces the mechanical oscillator by more than its zero-point uncertainty. We show that in this limit the power spectrum has multiple sidebands and that the cavity response has several resonances in the resolved-sideband limit. Using master-equation simulations, we also study the crossover from the weak-coupling many-photon to the single-photon strong-coupling regime. Finally, we find non-Gaussian steady-states of the mechanical oscillator when multi-photon transitions are resonant. Our study provides the tools to detect and take advantage of this novel regime of optomechanics.Comment: 4 pages, 4 figure

The photon blockade effect in optomechanical systems

We analyze the photon statistics of a weakly driven optomechanical system and discuss the effect of photon blockade under single photon strong coupling conditions. We present an intuitive interpretation of this effect in terms of displaced oscillator states and derive analytic expressions for the cavity excitation spectrum and the two photon correlation function $g^{(2)}(0)$. Our results predict the appearance of non-classical photon correlations in the combined strong coupling and sideband resolved regime, and provide a first detailed understanding of photon-photon interactions in strong coupling optomechanics

Defect-Suppressed Atomic Crystals in an Optical Lattice

We present a coherent filtering scheme which dramatically reduces the site occupation number defects for atoms in an optical lattice, by transferring a chosen number of atoms to a different internal state via adiabatic passage. With the addition of superlattices it is possible to engineer states with a specific number of atoms per site (atomic crystals), which are required for quantum computation and the realisation of models from condensed matter physics, including doping and spatial patterns. The same techniques can be used to measure two-body spatial correlation functions. We illustrate these ideas with a scheme to study the creation of a BCS state with a chosen filling factor from a degenerate Fermi gas in an optical lattice.Comment: 4 Pages, 5 Figures, REVTex

Influence of monolayer contamination on electric-field-noise heating in ion traps

Electric field noise is a hinderance to the assembly of large scale quantum computers based on entangled trapped ions. Apart from ubiquitous technical noise sources, experimental studies of trapped ion heating have revealed additional limiting contributions to this noise, originating from atomic processes on the electrode surfaces. In a recent work [A. Safavi-Naini et al., Phys. Rev. A 84, 023412 (2011)] we described a microscopic model for this excess electric field noise, which points a way towards a more systematic understanding of surface adsorbates as progenitors of electric field jitter noise. Here, we address the impact of surface monolayer contamination on adsorbate induced noise processes. By using exact numerical calculations for H and N atomic monolayers on an Au(111) surface representing opposite extremes of physisorption and chemisorption, we show that an additional monolayer can significantly affect the noise power spectrum and either enhance or suppress the resulting heating rates.Comment: 8 pages, 5 figure

Self assembling magnetic tiles

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (p. 27).Self assembly is an emerging technology in the field of manufacturing. Inspired by nature's ability to self assembly proteins from amino acids, this thesis attempts to demonstrate self assembly on the macro-scale. The primary focus of the thesis was to improve the design of magnetic tile self assembly. By constructing a flexible chain embedded with permanent magnets, self assembly is achieved through magnetic interaction. Theory has shown that such a chain is capable of self assembling into any 3D shape without self-intersection. The 3D shape created by the chain is predetermined by the sequence of the tiles. For this thesis, two chains were manufactured, each self assembling into one distinct shape. One chain self assembled into a sphere while the other self assembled into a '3-leaf clover'. An important characteristic shared by the two chains is that they both were constructed from 48 tiles that had the same proportion of north-pole and south-pole facing magnets. The difference between the two 3D shapes created is a direct result of the magnet tile sequencing, only. To connect the tiles, two different types of connectors were designed: one rigid and one flexible.(cont.) The rigid connector design was able to stabilize the chain geometry; however some joints displayed excessive rotational friction. Additionally, the chain was not robust and was easily broken if dropped. When the chain was manufactured using flexible connectors, the amount of friction in the joints was significantly reduced. However, the chain lost geometric stability since the flexible connectors could not overcome some torsion forces created by the magnets. Ultimately, this thesis provided supporting data for the theoretical arguments concerning the ability of a flexible chain to self assemble into arbitrary 3D shapes. By predetermining a sequence of magnetic tiles, it can be known with certainty what shape the chain will assume. This thesis furthered the understanding of the mechanisms of self assembly, providing groundwork for the eventual application on the nano-scale.by Jessica A. Rabl.S.B

When bad becomes worse: unethical corporate behavior may hamper consumer acceptance of cultured meat

Cultured meat is an emerging food innovation that promises to be a more sustainable alternative to conventional meat. However, despite its potential health, environmental and animal welfare benefits, research suggests that consumer acceptance of cultured meat is not assured. Across two pre-registered experimental studies (N = 456), this article investigates the extent to which two different credence characteristics, namely corporate social responsibility (Study 1) and food safety (Study 2), lead to halo-based inferences that may affect the consumer acceptance of cultured meat. Results indicate that, whereas the halo effect of positive corporate behavior is negligible, negative corporate behavior yields a substantial negative halo effect on consumers’ attitudes towards cultured meat, which in turn decreases acceptance of cultured meat. Findings also reveal that these negative halo-based inferences are heightened among consumers who value highly corporate social responsibility (Study 1) and food safety (Study 2). Overall, this article reveals an asymmetric halo effect by showing that people tend to react strongly to negative, but not to positive, information about a cultured meat company. The implications of the present research are discussed in the conclusion

Precision radial velocities of double-lined spectroscopic binaries with an iodine absorption cell

A spectroscopic technique employing an iodine absorption cell (I_2) to superimpose a reference spectrum onto a stellar spectrum is currently the most widely adopted approach to obtain precision radial velocities of solar-type stars. It has been used to detect ~80 extrasolar planets out of ~130 know. Yet in its original version, it only allows us to measure precise radial velocities of single stars. In this paper, we present a novel method employing an I_2 absorption cell that enables us to accurately determine radial velocities of both components of double-lined binaries. Our preliminary results based on the data from the Keck I telescope and HIRES spectrograph demonstrate that 20-30 m/s radial velocity precision can be routinely obtained for "early" type binaries (F3-F8). For later type binaries, the precision reaches ~10 m/s. We discuss applications of the technique to stellar astronomy and searches for extrasolar planets in binary systems. In particular, we combine the interferometric data collected with the Palomar Testbed Interferometer with our preliminary precision velocities of the spectroscopic double-lined binary HD 4676 to demonstrate that with such a combination one can routinely obtain masses of the binary components accurate at least at the level of 1.0%.Comment: Accepted for publication in The Astrophysical Journa