Squeezed light from an oscillator measured at the rate of oscillation

Sufficiently fast continuous measurements of the position of an oscillator approach measurements projective on position eigenstates. We evidence the transition into the projective regime for a spin oscillator within an ensemble of 2 × 1010 room-temperature atoms by observing correlations between the quadratures of the meter light field. These correlations squeeze the fluctuations of one light quadrature below the vacuum level. When the measurement is slower than the oscillation, we generate 11 . 5 - 1.5 + 2.5 dB and detect 8 . 5 - 0.1 + 0.1 dB of squeezing in a tunable band that is a fraction of the resonance frequency. When the measurement is as fast as the oscillation, we detect 4.7 dB of squeezing that spans more than one decade of frequencies below the resonance. Our results demonstrate a new regime of continuous quantum measurements on material oscillators, and set a new benchmark for the performance of a linear quantum sensor.

Acoustic frequency atomic spin oscillator in the quantum regime

Quantum noise reduction and entanglement-enhanced sensing in the acoustic frequency range is an outstanding challenge relevant for a number of applications including magnetometry and broadband noise reduction in gravitational wave detectors. Here we experimentally demonstrate quantum behavior of a macroscopic atomic spin oscillator in the acoustic frequency range. Quantum back-action of the spin measurement, ponderomotive squeezing of light, and virtual spring softening are observed at oscillation frequencies down to the sub-kHz range. Quantum noise sources characteristic of spin oscillators operating in the near-DC frequency range are identified and means for their mitigation are presented.

Prediction-Retrodiction Measurements for Teleportation and Conditional State Transfer

Regular measurements allow predicting the future and retrodicting the past of quantum systems. Time-nonlocal measurements can leave the future and the past uncertain, yet establish a relation between them. We show that continuous time-nonlocal measurements can be used to transfer a quantum state via teleportation or direct transmission. Considering two oscillators probed by traveling fields, we analytically identify strategies for performing the state transfer perfectly across a wide range of linear oscillator-field interactions beyond the pure beam-splitter and two-mode-squeezing types.

Microwave-to-optical transduction using a mechanical supermode for coupling piezoelectric and optomechanical resonators

The successes of superconducting quantum circuits at local manipulation of quantum information and photonics technology at long-distance transmission of the same have spurred interest in the development of quantum transducers for efficient, low-noise, and bidirectional frequency conversion of photons between the microwave and optical domains. We propose to realize such functionality through the coupling of electrical, piezoelectric, and optomechanical resonators. The coupling of the mechanical subsystems enables formation of a resonant mechanical supermode that provides a mechanically-mediated, efficient single interface to both the microwave and optical domains. The conversion process is analyzed by applying an equivalent circuit model that relates device-level parameters to overall figures of merit for conversion efficiency η and added noise N. These can be further enhanced by proper impedance matching of the transducer to an input microwave transmission line. The performance of potential transducers is assessed through finite-element simulations, with a focus on geometries in GaAs, followed by considerations of the AlN, LiNbO3, and AlN-on-Si platforms. We present strategies for maximizing η and minimizing N, and find that simultaneously achieving η > 50 % and N < 0.5 should be possible with current technology. We find that the use of a mechanical supermode for mediating transduction is a key enabler for high-efficiency operation, particularly when paired with an appropriate microwave impedance matching network. Our comprehensive analysis of the full transduction chain enables us to outline a development path for the realization of high-performance quantum transducers that will constitute a valuable resource for quantum information science.

Photon propagation through dissipative Rydberg media at large input rates

We study the dissipative propagation of quantized light in interacting Rydberg media under the conditions of electromagnetically induced transparency. Rydberg blockade physics in optically dense atomic media leads to strong dissipative interactions between single photons. The regime of high incoming photon flux constitutes a challenging many-body dissipative problem. We experimentally study in detail the pulse shapes and the second-order correlation function of the outgoing field and compare our data with simulations based on two novel theoretical approaches well-suited to treat this many-photon limit. At low incoming flux, we report good agreement between both theories and the experiment. For higher input flux, the intensity of the outgoing light is lower than that obtained from theoretical predictions. We explain this discrepancy using a simple phenomenological model taking into account pollutants, which are nearly stationary Rydberg excitations coming from the reabsorption of scattered probe photons. At high incoming photon rates, the blockade physics results in unconventional shapes of measured correlation functions.

Unconditional Steady-State Entanglement in Macroscopic Hybrid Systems by Coherent Noise Cancellation

The generation of entanglement between disparate physical objects is a key ingredient in the field of quantum technologies, since they can have different functionalities in a quantum network. Here we propose and analyze a generic approach to steady-state entanglement generation between two oscillators with different temperatures and decoherence properties coupled in cascade to a common unidirectional light field. The scheme is based on a combination of coherent noise cancellation and dynamical cooling techniques for two oscillators with effective masses of opposite signs, such as quasispin and motional degrees of freedom, respectively. The interference effect provided by the cascaded setup can be tuned to implement additional noise cancellation leading to improved entanglement even in the presence of a hot thermal environment. The unconditional entanglement generation is advantageous since it provides a ready-to-use quantum resource. Remarkably, by comparing to the conditional entanglement achievable in the dynamically stable regime, we find our unconditional scheme to deliver a virtually identical performance when operated optimally.

Correlated Photon Dynamics in Dissipative Rydberg Media

Rydberg blockade physics in optically dense atomic media under the conditions of electromagnetically induced transparency (EIT) leads to strong dissipative interactions between single photons. We introduce a new approach to analyzing this challenging many-body problem in the limit of a large optical depth per blockade radius. In our approach, we separate the single-polariton EIT physics from Rydberg-Rydberg interactions in a serialized manner while using a hard-sphere model for the latter, thus capturing the dualistic particle-wave nature of light as it manifests itself in dissipative Rydberg-EIT media. Using this approach, we analyze the saturation behavior of the transmission through one-dimensional Rydberg-EIT media in the regime of nonperturbative dissipative interactions relevant to current experiments. Our model is able to capture the many-body dynamics of bright, coherent pulses through these strongly interacting media. We compare our model with available experimental data in this regime and find good agreement. We also analyze a scheme for generating regular trains of single photons from continuous-wave input and derive its scaling behavior in the presence of imperfect single-photon EIT.

High-capacity spatial multimode quantum memories based on atomic ensembles

We study spatial multimode quantum memories based on light storage in extended ensembles of Λ-type atoms. We show that such quantum light-matter interfaces allow for highly efficient storage of many spatial modes. In particular, forward operating memories possess excellent scaling with the important physical parameters: quadratic scaling with the Fresnel number and even cubic with the optical depth of the atomic ensemble. Thus, the simultaneous use of both the longitudinal and transverse shape of the stored spin wave modes constitutes a valuable and so far overlooked resource for multimode quantum memories.

RESPIRATION OF RAT PERITONEAL MAST CELLS

Methods for microgasometry of a few hundred mast cells are described. The Cartesian ampulla diver technique is used. The sample size is determined by counting the cells within the diver. The respiration rates at 37°C, expressed in microliters per cell per hour, are 0.29 x 10^-6 without substrate and 0.47 x 10^-6 with glucose.

Water transport by GLUT2 expressed in Xenopus laevis oocytes

The glucose transporter GLUT2 has been shown to also transport water. In the present paper we investigated the relation between sugar and water transport in human GLUT2 expressed in Xenopus oocytes. Sugar transport was determined from uptakes of non-metabolizable glucose analogues, primarily 3-O-methyl-D-glucopyranoside; key experimental results were confirmed using D(+)-glucose. Water transport was derived from changes in oocyte volume monitored at a high resolution (20 pl, 1 s). Expression of GLUT2 induced a sugar permeability, P(S), of about 5 x 10(-6) cm s(-1) and a passive water permeability, L(p), of 5.5 x 10(-5) cm s(-1). Accordingly, the passive water permeability of a GLUT2 protein is about 10 times higher than its sugar permeability. Both permeabilities were abolished by phloretin. Isosmotic addition of sugar to the bathing solution (replacing mannitol) induced two parallel components of water influx in GLUT2, one by osmosis and one by cotransport. The osmotic driving force arose from sugar accumulation at the intracellular side of the membrane and was given by an intracellular diffusion coefficient for sugar of 10(-6) cm(2) s(-1), one-fifth of the free solution value. The diffusion coefficient was determined in oocytes coexpressing GLUT2 and the water channel AQP1 where water transport was predominantly osmotic. By the cotransport mechanism about 35 water molecules were transported for each sugar molecule by a mechanism within the GLUT2. These water molecules could be transported uphill, against an osmotic gradient, energized by the flux of sugar. This capacity for cotransport is 10 times smaller than that of the Na(+)-coupled glucose transporters (SGLT1). The physiological role of GLUT2 for intestinal transport under conditions of high luminal sugar concentrations is discussed.

Water transport by Na+-coupled cotransporters of glucose (SGLT1) and of iodide (NIS). The dependence of substrate size studied at high resolution

The relation between substrate and water transport was studied in Na+-coupled cotransporters of glucose (SGLT1) and of iodide (NIS) expressed in Xenopus oocytes. The water transport was monitored from changes in oocyte volume at a resolution of 20 pl, more than one order of magnitude better than previous investigations. The rate of cotransport was monitored as the clamp current obtained from two-electrode voltage clamp. The high resolution data demonstrated a fixed ratio between the turn-over of the cotransporter and the rate of water transport. This applied to experiments in which the rate of cotransport was changed by isosmotic application of substrate, by rapid changes in clamp voltage, or by poisoning. Transport of larger substrates gave rise to less water transport. For the rabbit SGLT1, 378+/-20 (n=18 oocytes) water molecules were cotransported along with the 2 Na+ ions and the glucose-analogue alpha-MDG (MW 194); using the larger sugar arbutin (MW 272) this number was reduced by a factor of at least 0.86+/-0.03 (15). For the human SGLT1 the respective numbers were 234+/-12 (18) and 0.85+/-0.8 (7). For NIS, 253+/-16 (12) water molecules were cotransported for each 2 Na+ and 1 thiocyanate (SCN-, MW 58), with I- as anion (MW 127) only 162+/-11 (19) water molecules were cotransported. The effect of substrate size suggests a molecular mechanism for water cotransport and is opposite to what would be expected from unstirred layer effects. Data were analysed by a model which combined cotransport and osmosis at the membrane with diffusion in the cytoplasm. The combination of high resolution measurements and precise modelling showed that water transport across the membrane can be explained by cotransport of water in the membrane proteins and that intracellular unstirred layers effects are minute.

Mobility of ions, sugar, and water in the cytoplasm of Xenopus oocytes expressing Na(+)-coupled sugar transporters (SGLT1)

A model was set up to study water transport in membrane proteins expressed in Xenopus oocytes. The model was tested experimentally using human and rabbit Na+-glucose cotransporters (SGLT1), and was used to explain controversies regarding unstirred layer effects. Cotransport of Na+, sugar and water was monitored by two-electrode voltage clamp and online measurements of oocyte volume. The specific resistance of the oocyte cytoplasm was found by means of microelectrodes to be 263 +/- 91 Omega cm (S.D., n = 52), or 2.5 times that of Kulori medium, in agreement with reported values of intracellular ion concentrations and diffusion constants. Osmotically induced volume and resistance changes were compatible with a model of the oocyte in which 37 +/- 17 % (S.D., n = 66) of the intracellular volume acts as a free solution while the remainder is inert, being occupied by organelles, etc. The model explains the results of several types of experiments: rapid changes in rates of water cotransport induced by changes in clamp voltage followed by osmotic equilibration in sugar-free conditions; volume changes induced by Na+ transport via the ionophore gramicidin; and uphill water transport. Ethanol (0.5 %) induced a marked swelling of the oocytes of about 16 pl x s(-1). If the specific inhibitor of SGLT1 phlorizin is added from stock solutions in ethanol, the effect of ethanol obfuscates the effects of the inhibitor. We conclude that the transport parameters derived for water cotransport by the SGLT1 can be attributed to the protein residing in the plasma membrane with no significant influences from unstirred layer effects.

Synergistic effects of p-fluorophenylalanine and supra-optimal temperatures on cell division in Tetrahymena pyriformis

The combined effects of sub-optimal (20 degrees) or supra-optimal (31 degrees C and 34 degrees C) temperatures and the amino acid analogue p-fluorophenylalanine on preparations for cell division in Tetrahymena pyriformis were analysed. A supra-optimal temperature of 31 degrees produced a marked exaggeration of the division-delaying capacity of the analogue. The analogue also sensitises cells when combined with the normal heat shock temperature of 34 degrees, which indicates that division proteins continue to be synthesized at this temperature but cannot be effectively utilized by the cell. These results support the model that preparations involve interactions between and formation of assemblies of proteins on a strict time schedule shortly before division.

Analysis of the time of utilization of proteins for the initiation and completion of division in synchronized Tetrahymena pyriformis

We exposed division-synchronized Tetrahymena pyriformis to pulse treatments with the structural amino acid analogue p-fluorophenylalanine. We related the timing of the treatments to the delays in onset or completion of division, or both. The results enable us to distinguish between early and late phases in cell division in which the cells bring into action proteins which contribute to initiate and complete division, respectively. Normally, these events are separated by 25–30 min.

Prevalence of Klinefelter's syndrome (47,XXY) in a general male population

In a representative sample of 3,840 males examined for military service chromosome examination was made in those with testes equal to or less than 12 ml and those with a stature equal to or greater than 181 cm, as well as in males not recruited because of physical or mental disability. Testes equal to or less than 12 ml were found in 59 patients (1.45%). Three of these males had a 47,XXY karyotype (5.1%), the prevalence among the total sample of 3,840 being 0.78 per 1,000. Hypogonadal signs, except for gynaecomastia, which was only present in one patient, were found in the saem proportion as in 47,XXY males ascertained in institutions and clinics. The results of EEG investigations were alos similar to those found in psychiatric institutions. The intelligence level was comparatively low; none had an IQ above 100. The personality traits corresponded to those found in institutionalized Klinefelter males.

Linear increase in glycolytic activity through the cell cycle of schizosaccharomyces pombe

The glycolytic activity of 3 different synchronous system in S. pombe was studied. Synchronous cultures were produced by a selection procedure, by cyclic heat treatment, or by cloning cells from an exponentially multiplying culture. In all experiments a complex medium with 3% glucose was used. The glycolytic activity was recorded with a gasometric method, the gradient diver. A single cell in exponential growth or a small number of synchronized cells were placed in ampulla divers in which the cells progressed undistrubed through a number of cycles. An ampulla diver is in principle a narrow pipette by which a single or a few cells are removed from the mother culture. It serves next as an axenic growth chamber and at the same time as a gasometer. The divers were placed in linear saline density gradients and the gaseous exchanges taking place in the divers resulted in migration of the divers. The migration rate is a measure of the glycolytic activity of the cells. Our results show that the glycolytic activity increases in a linear fashion between sucessive divisions. The rate of increase doubles at each division. This true in all 3 synchronous systems, and we take this as an indication that the cell cycles of heat-synchronized cells do not deviate seriously from the normal.

A psychiatric-psychological study of XYY males found in a general male population

The psychological test results of five XYY males from in a population study showed an intellectual level within the normal range but with a mean full scale IQ and educational level lower than expected. The cognitive as well as emotional function was characterized by immaturity, manifested in passivity, unreflectiveness and emotional liability, in three resulting in uncontrolled aggressive outbursts. Conflict material also appeared immaturely resolved, centering around unfulfilled needs of contact and insecure masculine identification. The defense mechanisms used were generally rather weak, but only in one subject did the anxiety level seem to be excessively low. All five males differed to a certain extent from their siblings; three of them were hyperactive, restless, hot-tempered and impulsive at school and four of them had difficulties at school. Three learned a trade, but only one stayed in his trade, and one was applying for disablement pension on account of personality deviation. Two of the five had a criminal record. It is concluded that the presence and degree of the above-mentioned characteristics of XYY males varied. It is evident that environmental factors play as great a role for the development of personality and behaviour in males with karyotype 47, XYY as in males with a normal chromosome constitution.

Cytochalasin B: Aspects of Phagocytosis in Nutrient Uptake in Tetrahymena

Cytochalasin B (37 µg per ml) reduces the rate of food vacuole formation, i.e. the rate of phagocytosis, in Tetrahymena pyriformis. Cytochalasin B in this concentration suppresses multiplication rates in a nutrient medium consisting of 2 % proteose peptone, but multiplication is unaffected if this medium is supplemented with glucose and high concentrations of nucleosides. Thus nutrients in high concentrations circumvent the necessity for phagocytosis in Tetrahymena.

D-D translocations in males examined for military service

Three males with Robertsonian translocations were found in a sample of 1115 males examined for military service. One was a 14/15 translocation, and two were 13/14 translocations. One was spontaneous and two familial. The segregation rate of the translocations did not deviate significantly from unity in the sibships where the mother was the carrier, whereas all five children had the translocation in the two sibships where the father was the carrier. There were no abortions and no aneuploid chromosome abnormalities in the progeny of carriers with D/D translocation. There were no indications of any association between the D/D translocations and physical or mental development.

Clonal Growth Of Mouse Cells (Strain L)

Clones of mouse fibroblast cells (strain L) have been cultivated in a nutrient-rich, complex medium in monolayer cultures. Cell multiplication was followed by time-lapse photography or video recording. In both cases exposures were made every hour, which is sufficiently frequent to keep track of the original cell and its progeny from the 1-cell stage to 128-cell stage, or for about a week. Cell lines were followed, ‘family trees’ were constructed and individual and average generation times were calculated in all cases.

The data showed that the average durations of at least 4 generations (from the fourth up to and including the seventh) were rather constant. Division synchrony deteriorated with time but could still be perceived at the end of 7 generations. As would be expected from these observations, the coefficient of variation of generation times within one single clone in our experimental system is low (about 9%), compared to previously reported values.

Studies Of The Effect Of Temperature Shocks On Preparation For Cell Division In Mouse Fibroblast Cells (L Cells)

As L cells go through their growth-division cycle they acquire the capacity to respond progressively more strongly to certain standard changes in the temperature of the environment. Using techniques described earlier, we found that chilling to 1, 6 or 10 °C for 1 h had little effect on the timing of the forthcoming division. Conversely, heating for 1 h to temperatures between 41 and 42 °C had a strong effect. Generally, the older the cell when heated, the more extended is its generation time; in other words, the longer is the forthcoming division postponed. We found evidence that late in the cycle the cells undergo transition from a state in which they are maximally delayed with respect to the performance of a division to one in which they are less delayed.

We attempted to synchronize cell divisions with single and with series of heat shocks (41.6 °C for 1 h). Like our predecessors in the field, we obtained only partial synchrony. However, because L cells appear to prepare for division between shocks, and because heat shocks tend to reverse such preparations for division, we find reason to continue these experiments, using previous experience with Tetrahymena and Schizosaccharomyces as a guide. Both the latter cells respond to proper temperature treatment with synchronous cell division.

Length of the Y chromosome in a general male population

Measurement of the Y chromosome has been made in 508 males examined for military service. There was a normal Gaussian distribution of the length of the Y chromosome.

The frequency of mentally retarded males was significantly higher than expected among those with a comparatively large Y (Y/F ≧ 1.00). It is concluded that there may be an association between the length of the Y chromosome and certain types of mental retardation.