Electromagnetically Induced Transparency in Circuit Quantum Electrodynamics with Nested Polariton States.

Quantum networks will enable extraordinary capabilities for communicating and processing quantum information. These networks require a reliable means of storage, retrieval, and manipulation of quantum states at the network nodes. A node receives one or more coherent inputs and sends a conditional output to the next cascaded node in the network through a quantum channel. Here, we demonstrate this basic functionality by using the quantum interference mechanism of electromagnetically induced transparency in a transmon qubit coupled to a superconducting resonator. First, we apply a microwave bias, i.e., drive, to the qubit-cavity system to prepare a Λ-type three-level system of polariton states. Second, we input two interchangeable microwave signals, i.e., a probe tone and a control tone, and observe that transmission of the probe tone is conditional upon the presence of the control tone that switches the state of the device with up to 99.73% transmission extinction. Importantly, our electromagnetically induced transparency scheme uses all dipole allowed transitions. We infer high dark state preparation fidelities of >99.39% and negative group velocities of up to -0.52±0.09 km/s based on our data.

Initialization by measurement of a superconducting quantum bit circuit.

We demonstrate initialization by joint measurement of two transmon qubits in 3D circuit quantum electrodynamics. Homodyne detection of cavity transmission is enhanced by Josephson parametric amplification to discriminate the two-qubit ground state from single-qubit excitations nondestructively and with 98.1% fidelity. Measurement and postselection of a steady-state mixture with 4.7% residual excitation per qubit achieve 98.8% fidelity to the ground state, thus outperforming passive initialization.

Quantum state tomography of an itinerant squeezed microwave field.

We perform state tomography of an itinerant squeezed state of the microwave field prepared by a Josephson parametric amplifier (JPA). We use a second JPA as a preamplifier to improve the quantum efficiency of the field quadrature measurement from 2% to 36%±4%. Without correcting for the detection inefficiency we observe a minimum quadrature variance which is 68(-7)(+9)% of the variance of the vacuum. We reconstruct the state's density matrix by a maximum likelihood method and infer that the squeezed state has a minimum variance less than 40% of the vacuum, with uncertainty mostly caused by calibration systematics.

Spatially band-tunable color-cone lasing emission in a dye-doped cholesteric liquid crystal with a photoisomerizable chiral dopant.

This study investigates a spatially band-tunable color-cone lasing emission (CCLE) based on a dye-doped cholesteric liquid crystal with a photoisomerizable chiral dopant (IBM). Experimental results show that the lasing band of the formed CCLE of the cell with a photoinduced pitch gradient can be spatially tuned among various color regions by adjusting the pumped position of the cell. The spatially band tunability of the laser results from the UV-irradiation-induced decrease of the helical twisting power of IBM via trans-->cis isomerization, accordingly shrinking the pitch of the cholesteric-liquid-crystal host. The total spatially tunable wavelength range for the laser exceeds 100 nm.

Low-noise kinetic inductance traveling-wave amplifier using three-wave mixing.

We have fabricated a wide-bandwidth, high dynamic range, low-noise cryogenic amplifier based on a superconducting kinetic inductance traveling-wave device. The device was made from NbTiN and consisted of a long, coplanar waveguide on a silicon chip. By adding a DC current and an RF pump tone we are able to generate parametric amplification using three-wave mixing. The devices exhibit gain of more than 15 dB across an instantaneous bandwidth from 4 to 8 GHz. The total usable gain bandwidth, including both sides of the signal-idler gain region, is more than 6 GHz. The noise referred to the input of the devices approaches the quantum limit, with less than 1 photon excess noise. Compared to similarly constructed four-wave mixing amplifiers, these devices operate with the RF pump at ~20 dB lower power and at frequencies far from the signal. This will permit easier integration into large scale qubit and detector applications.

Microwave facilities for welding thermoplastic composites and preliminary results.

The wide range of applications of microwave technology in manufacturing industries has been well documented (NRC, 1994; Thuery, 1992). In this paper, a new way of joining fibre reinforced thermoplastic composites with or without primers is presented. The microwave facility used is also discussed. The effect of power input and cycle time on the heat affected zone (HAZ) is detailed together with the underlying principles of test piece material interactions with the electromagnetic field. The process of autogenous joining of 33% by weight of random glass fibre reinforced Nylon 66, polystyrene (PS) and low density polyethylene (LDPE) as well as 23.3% by weight of carbon fibre reinforced PS thermoplastic composites is discussed together with developments using filler materials, or primers in the heterogenous joining mode. The weldability dependence on the dielectric loss tangent of these materials at elevated temperatures is also described.

Permittivity measurement of thermoplastic composites at elevated temperature.

The material properties of greatest importance in microwave processing of a dielectric are the complex relative permittivity epsilon = epsilon'-jepsilon", and the loss tangent, tan delta = epsilon"/epsilon'. This paper describes two convenient laboratory based methods to obtain epsilon', epsilon" and hence tan delta of fibre-reinforced thermoplastic (FRTP) composites. One method employs a microwave network analyzer in conjunction with a waveguide transmission technique, chosen because it provides the widest possible frequency range with high accuracy. The values of the dielectric constant and dielectric loss of glass fibre reinforced (33%) low density polyethylene, LDPE/GF (33%), polystyrene, PS/GF (33%), and Nylon 66/GF (33%), were obtained. Results are compared with those obtained by another method using a high-temperature dielectric probe.

Variables Affecting the CO(2) Compensation Point.

Some factors influencing dark respiration, photorespiration, and photosynthesis were examined for their effect on the CO(2) compensation point (70 mul/l) of detached soybean (Glycine max) leaf discs. A higher compensation point in young leaves decreased to the constant value after leaf expansion and maturation, but increased again during senescence. The compensation point was 40 to 50% higher in plants grown in the summer than in the winter. The compensation point and dark respiration increased with temperatures above 17 C. Below 17 C dark respiration continued to decrease, but the compensation point did not decrease further. Increasing light intensities did not affect the compensation point.The effect of selected chemicals on the compensation point were surveyed. Some buffer components did not greatly alter the compensation point but organic solvents lowered it. Potassium phosphate and pyrophosphate greatly increased it. Inhibitors of photosynthesis increased the compensation point. Hydroxypyridinemethanesulfonate and sodium bisulfite severely inhibited photosynthesis in soybean leaves, stimulated dark respiration, and increased the compensation point.

Stimulation of rice coleoptile growth by ethylene.

The growth rate of rice coleoptiles is increased by low concentrations of ethylene, especially in oxygen concentrations lower than air; carbon dioxide enhanced this response. C2H4 is produced by rice seedlings, and this production is also enhanced by carbon dioxide. Ethane and propane were produced in trace amounts but were inactive in growth stimulation as were also methane, propylene, and butane.

Isolation of active mitochondria from tomato fruit.

An improved method for isolating mitochondria from tomato fruit (Lycopersicon esculentum Mill.) is described. The fruit is chilled, and the tissue of the fruit wall cut by hand into very thin slices with a razor blade while immersed in a buffer containing 0.4 m sucrose, 2 mm MgCl(2), 8 mm EDTA, 4 mm cysteine, 10 mm KCl, 0.5 mg per ml bovine serum albumin 50 mm tris-HCl, pH 7.6. The pH is monitored and kept within the range of 7.0 to 7.2 by dropwise addition of 1 n KOH during cutting. The tissue is strained through 8 layers of cheesecloth and centrifuged at 2000 x g for 15 minutes. The supernatant is then centrifuged at 11,000 x g for 20 minutes, and the sediment is washed once with a medium containing 0.4 m sucrose, 10 mm KCl, 1 mm MgCl(2), 10 mm tris-HCl, 10 mm KH(2)PO(4) and bovine serum albumin (0.5 mg per ml), pH 7.2. Electron microscope studies show that this method gives homogeneous, relatively intact mitochondria; they have a higher respiratory control ratio than those reported by other workers. The method was also tested successfully on fruits of cantaloupe and ;Honey Dew' melon.