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Biomedical subjects

C Monroe

Publications and source records attributed to C Monroe.

17 recordsLinked to original sources
PubMed2000

Experimental entanglement of four particles

Quantum mechanics allows for many-particle wavefunctions that cannot be factorized into a product of single-particle wavefunctions, even when the constituent particles are entirely distinct. Such 'entangled' states explicitly demonstrate the non-local character of quantum theory, having potential applications in high-precision spectroscopy, quantum communication, cryptography and computation. In general, the more particles that can be entangled, the more clearly nonclassical effects are exhibited--and the more useful the states are for quantum applications. Here we implement a recently proposed entanglement technique to generate entangled states of two and four trapped ions. Coupling between the ions is provided through their collective motional degrees of freedom, but actual motional excitation is minimized. Entanglement is achieved using a single laser pulse, and the method can in principle be applied to any number of ions.

Journal Article↗
PubMed2000

Decoherence of quantum superpositions through coupling to engineered reservoirs

The theory of quantum mechanics applies to closed systems. In such ideal situations, a single atom can, for example, exist simultaneously in a superposition of two different spatial locations. In contrast, real systems always interact with their environment, with the consequence that macroscopic quantum superpositions (as illustrated by the 'Schrodinger's cat' thought-experiment) are not observed. Moreover, macroscopic superpositions decay so quickly that even the dynamics of decoherence cannot be observed. However, mesoscopic systems offer the possibility of observing the decoherence of such quantum superpositions. Here we present measurements of the decoherence of superposed motional states of a single trapped atom. Decoherence is induced by coupling the atom to engineered reservoirs, in which the coupling and state of the environment are controllable. We perform three experiments, finding that the decoherence rate scales with the square of a quantity describing the amplitude of the superposition state.

Journal Article↗
PubMed1996

A "Schrodinger Cat" Superposition State of an Atom

A "Schrodinger cat"-like state of matter was generated at the single atom level. A trapped 9Be+ ion was laser-cooled to the zero-point energy and then prepared in a superposition of spatially separated coherent harmonic oscillator states. This state was created by application of a sequence of laser pulses, which entangles internal (electronic) and external (motional) states of the ion. The Schrodinger cat superposition was verified by detection of the quantum mechanical interference between the localized wave packets. This mesoscopic system may provide insight into the fuzzy boundary between the classical and quantum worlds by allowing controlled studies of quantum measurement and quantum decoherence.

Journal Article↗
PubMed1989

Olfactory function in chemical workers exposed to acrylate and methacrylate vapors.

An investigation of the olfactory function of 731 workers at a chemical facility which manufacturers acrylates and methacrylates was undertaken using a standardized quantitative test. In a cross-sectional analysis of the data, no associations of chemical exposure with olfactory test scores were observed. A nested case-control study designed to evaluate the cumulative effects of exposure on olfactory function, however, revealed elevated crude exposure odds ratios (95% confidence interval) of 2.0 (1.1, 3.8) for all workers and 6.0 (1.7, 21.5) for workers who never smoked cigarettes. Logistic regression analysis, adjusting for multiple confounders, revealed exposure odds ratios of 2.8 (1.1, 7.0) and 13.5 (2.1, 87.6) in these same groups, respectively, and a dose-response relationship between olfactory dysfunction and cumulative exposure scores--semi-quantitative indices of lifetime exposure to the acrylates. The data also revealed decreasing exposure odds ratios with increasing duration since last exposure to these chemicals, suggesting that the effects may be reversible.

Acrylates↗
PubMed1986

Quantitative assessment of olfactory function in an industrial setting.

The University of Pennsylvania Smell Identification Test (UPSIT) was administered, on a volunteer basis, to workers frequenting the cafeteria of the corporate offices of a major chemical manufacturing company to (1) establish the level of acceptance of self-administered olfactory testing within such a setting, (2) determine the percentage of the sample that reported or evidenced marked olfactory impairment, and (3) develop guidelines for the use of the UPSIT as a corporate medical surveillance tool. The initial acceptance of the testing program was high. Thus, 640 of the cafeteria visitors agreed to take the test (total work force in building less than 1,000). However, only 52% of the tests handed out were completed by the employees and returned to the test examiners, possibly reflecting the informal atmosphere in which they were distributed. Of the group returning the tests, seven employees reported having smell problems due to allergies or sinus disease. However, all of these employees had normal UPSIT scores. Three subjects (1% of the sample) evidenced marked olfactory dysfunction. Of these three, only one was aware of the problem before testing. On average, the corporate subjects significantly outperformed matched control subjects obtained from previous administrations of the UPSIT at health fairs and other public events, although the difference was less than half a point (37.89 v 37.53; P less than .004). As in previous studies, the test scores of women were slightly, but significantly, higher than those of men (respective means = 37.98 v 37.80, P less than .04).

Adult↗