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For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequisite for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This principle applies to stones, feathers, and atoms alike. Under conditions of microgravity, very long and precise measurements can be carried out to determine whether different types of atoms actually "fall equally fast" in the gravitational field of the Earth – or if we have to revise our understanding of the universe.As part of a national consortium, Ferdinand-Braun-Institut, Leibniz-Institut fuer Hoechstfrequenztechnik (FBH) and Humboldt-Universitaet zu Berlin (HU) now made a historical step towards testing the Equivalence Principle in the microcosm of quantum objects. In the MAIUS mission launched on January 23, 2017 a cloud of nano-Kelvin cold rubidium atoms has been generated in space for the first time ever. This cloud was cooled down with laser light and radio frequency electrical fields so that the atoms finally formed a single quantum object, a Bose-Einstein condensate (BEC).More than 20 years after the groundbreaking results of the Nobel laureates Cornell, Ketterle, and Wieman on ultra-cold atoms, preliminary evaluation of the sounding rocket mission data indicates that such experiments can also be carried out under the harsh conditions of space operation – back in 1995, living room-sized setups in a special laboratory environment were required. Today's quantum optical sensor is as small as a freezer and remains fully operational even after experiencing huge mechanical and thermal stress caused by the rocket launch. This groundbreaking mission is a pathfinder for applications of quantum sensors in space. In the future, scientists expect to use quantum sensor technology to cope with one of the biggest challenges of modern physics: the unification of gravitation with the other fundamental interactions (strong, weak, and electro-magnetic force) in a single consistent theory. At the same time, these experiments are drivers of innovation for a broad range of applications, from inertial (non-GPS referenced) navigation to space-borne geodesy used to determine the Earth's shape.For this mission, the FBH has developed hybrid micro-integrated semiconductor laser modules that are suitable for application in space. These laser modules, together with optical and spectroscopic units provided by third partners, have been integrated and qualified by HU to provide the laser subsystem of the scientific payload. The results of this mission coordinated by Leibniz Universitaet Hannover do not only prove that quantum optical experiments with ultra-cold atoms are possible in space, but also give FBH and HU the opportunity to test their miniaturized laser system technology under real operating conditions. The results will also be used to prepare future missions which are already scheduled for launch. MAIUS, however, is not the first sounding rocket test for both institutions' laser technology in space; the technology has already been successfully tested in April 2015 and January 2016 on board of two sounding rockets within the FOKUS and KALEXUS experiments.  The MAIUS mission is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry of Economic Affairs and Energy and tests all key technologies of a space-borne quantum optical sensor on a sounding rocket: vacuum chamber, laser system, electronics, and software. MAIUS constitutes a historical milestone for future missions in space that will take advantage of the full potential of quantum technology. For the first time world-wide, a Bose-Einstein condensate (BEC) based on rubidium atoms has been created on board of a sounding rocket and has been used to investigate atom interferometry in space. Quantum optical sensors based on BECs enable high-precision measurements of accelerations and rotations using laser pulses which provide a reference for precise determination of the positions of the atomic cloud.The compact and robust diode laser system for laser cooling and atom interferometry with ultra-cold rubidium atoms has been developed under the leadership of the Optical Metrology Group at HU. This system is required for the operation of the MAIUS experiment and consists of four diode laser modules that have been developed by FBH as hybrid-integrated master-oscillator power-amplifier laser modules. The master laser is a monolithic distributed feedback (DFB) laser which is frequency-stabilized to the frequency of an optical transition in rubidium and generates spectrally pure and highly stable (~ 1 MHz linewidth) optical radiation with low output power at 780 nm wavelength. The three other laser modules feature a tapered amplifier chip with a ridge waveguide input section. These tapered amplifier chips boost the optical output power of a DFB laser to beyond 1 W without any loss of spectral stability. Two additional redundancy modules were integrated. Free space acousto-optical modulators and optical components are used to generate the laser pulses according to the experimental sequence. The laser light pulses are finally transferred to the experimental chamber by optical fibers.Furthermore, a laser technology demonstrator designed for future missions has been integrated, consisting of two micro-integrated semiconductor Extended Cavity Diode Laser modules developed by FBH. These modules are specifically required for future atom interferometry experiments that pose more stringent requirements on the spectral stability of the lasers.Reference:GP1A173LCS2FOPB626GP1A53HRJ00F  

Designed for precision angle measurement, Contelec’s Vert-X 48E series non-contacting magnetic encoder is aimed at applications in agriculture, mining or construction equipment, and other applications where extreme environmental conditions exist and accurate control is required for steering, guiding or positioning etc.Available with full product and application engineering support from Variohm EuroSensor, the new sensor is a two-part design with no mechanical bearing or joint between the magnet and sensor components.The 48mm diameter and 17mm high sensor housing is fully sealed to IP68/IP69K and a choice of magnet designs allows maximum installation flexibility. The Vert-X 48E has resolution options of 12- or 14-bits with a choice of single and redundant output types for 0..10 V, and 4…20mA as well as single and redundant CANopen versions. The supply voltage of 8…35VDC will suit various position feedback tasks.With simple installation between rotating and stationary components in steering, drive chain, guide or other transmission mechanics, the sensor works with an air-gap of up to 13mm depending on the sensor type and an optional ‘detection of magnetic loss’ feature will signal a system shut-down in case of the magnetic actuator moving out of a valid air-gap range.The axial alignment allows up to 13mm between the sensor and magnet rotation axes as well as a good tolerance of tilting and radial misalignment. These factors combine with outstanding resilience to humidity, damp and dust as well as EN 60068-2-6 shock and EN 60068-2-27 vibration rated mechanical specifications, for exceptional levels of reliability and endurance.Other options for the range include selectable electrical angle in ten degree steps up to 360 degrees, settable mid-point, start and end point and gradient. One metre cable connection is standard with customised lengths and special connector options available on request. Reference:350-00029ALS-PT17-51C/L177/TR8EE-TP405-X  

New Yorker Electronics has introduced a series ruggedised aluminium electrolytic capacitors with welded seals, the MLSG in both Flatpack and Slimpack. This series targets compact power supply applications in military and aerospace, as well as other critical systems.Design enhancements and an electrolyte push the MLSG to nearly double the operating life of its predecessor, the MLSH, at no added cost.Two principal package profiles are offered in this technology, the MLSG Flatpack which measures just 0.5" thick and 1.75" wide and the MLSG Slimpack measuring 0.5" thick by 1" wide, both offered in lengths of 1.5, 2, 2.5 or 3".MLSG Flatpack welded seals capacitors can be made to withstand up to 50g vibrations (10g standard) and altitudes greater than 80,000ft. With stainless steel cases and near hermetic welded seals, they are built for extended duty in very harsh conditions. Especially noteworthy is that a high level of performance is maintained over the full operating temperature range. Capacitance retention at -55°C is very strong, with excellent high temperature performance up to 125°C. The new electrolyte system is fully REACH compliant, allowing application of the components in a broad range of applications where space efficiency and extraordinarily long life are required.A wide range of standard capacitance values from 220 to 24,000µF are available, with voltage ratings up to 250VDC. The unique flat package design does more than save space. It is easily cooled, and can offer flexibility in ganging two or more devices in ways that conventional electrolytics can’t.Options include High Vibration (HVMLSG), for performance to 50g, and High Reliability (HRMLSG), with burn-in at rated voltage and 85°C. Where a true glass-to-metal hermetic seal is required, CDE offers the MLSH Slimpack, which is similarly constructed in a flat stainless steel package. It is available in nine values, from 120 to 3,200µF, with ratings up to 250VDC.With a profile of 1x0.5", the MLSG Slimpack welded seals capacitors fit into the tightest of spaces and meet a DC test of 5,000 hours at rated voltage, 125°C. MLSG Slimpack is a perfect fit for military and aerospace applications requiring a low profile, rugged design and long-life. The MSGL Slimpack is also available in an HRMLSG type for high reliability burn-in – and is rated to vibration levels of 80g.Features and benefits5,000 hours at rated voltage of 125°CStainless steel caseWithstands more than 80,000ft. altitudeType HR, high reliability burn-inType HV, high vibration levelsFlatpack to 50g; Slimpack to 80gApplicationsAerospaceMilitaryCritical systemsPower suppliesReference:F17724102900MKP1841410254BFC246816474 

Scientists often discover interesting things without completely understanding how they work. That has been the case with an experimental memory technology in which temperature and voltage work together to create the conditions for data storage. But precisely how was unknown. But when a Stanford team found a way to untangle the chip’s energy and heat requirements, their tentative findings revealed a pleasant surprise: The process may be more energy efficient than was previously supposed.That’s good news for next-generation mobile devices whose batteries would last longer if they were powering lower energy chips. The group that made this discovery, led by Stanford electrical engineer H.-S. Philip Wong, is presenting the paper when the IEEE International Electron Devices Meeting (IEDM) brings leading researchers to San Francisco Dec. 5.The new technology the team investigated is called resistive random-access memory, or RRAM for short. RRAM is based on a new type of semiconductor material that forms digital zeros and ones by resisting or permitting the flow of electrons.RRAM has the potential to do things that aren’t possible with silicon: for instance, being layered on top of computer transistors in new three-dimensional, high-rise chips that would be faster and more energy efficient than current electronics, which is ideal for smartphones and other mobile devices where energy efficiency is a vital feature.But while engineers can observe that RRAM does store data, they don’t know exactly how these new materials work. “We need much more precise information about the fundamental behavior of RRAM before we can hope to produce reliable devices,” Wong said. So to help engineers understand some of the unknowns, Wong’s team built a tool to measure the basic forces that make RRAM chips work.Graduate student Zizhen Jiang of the Stanford team explained the basics: RRAM materials are insulators, which normally do not allow electricity to flow, she said. But under certain circumstances, insulators can be induced to let electrons flow.Past research had shown how: Jolting RRAM materials with an electric field causes a pathway to form that permitted electron flows. This pathway is called a filament. To break the filament, researchers apply another jolt and the material becomes an insulator again. So each jolt switched the RRAM from zero to one or back, which is what makes the material useful for data storage.But electricity is not the only force at play in RRAM switching. Pumping electrons into any material raises its temperature. That’s the principle behind electric stoves. In the case of RRAM, it was the elevated temperature caused by introducing voltage that induced filaments to form or break. The question was what voltage-induced temperature was needed to cause the switching. No one knew.Before the new Stanford study researchers thought short bursts of voltage, sufficient to generate temperatures of about 1,160ºF – hot enough to melt aluminum – was the switching point. But those were estimates because there was no way to measure the heat generated by an electric jolt. “In order to begin to answer our questions, we had to decouple the effects of voltage and temperature on filament formation,” said Ziwen Wang, another graduate student on the team.Essentially, the Stanford researchers had to heat the RRAM material without using an electric field. So they put an RRAM chip on a micro thermal stage (MTS) device – a sophisticated hot plate capable of generating a wide range of temperatures inside the material.Of course the objective was not merely to heat the material, but also to measure how filaments formed. Here they took advantage of the fact that RRAM materials are insulators in their natural state. That makes them digital zeros. As soon as a filament formed electrons would flow. The digital zero would become a digital one, which the researchers could detect.Using this experimental model, the team put RRAM chips on the burner and cranked up the heat, starting at about 80ºF – roughly the temperature of a warm room – all the way up to 1,520ºF, hot enough to melt a silver coin. Heating the RRAM to various temperatures in between these extremes, the researchers measured precisely if and how RRAM switched from its native zero to a digital one.To their pleasant surprise, the researchers observed that filaments could form more efficiently at ambient temperatures between 80ºF and 260ºF, which is hotter than boiling water – contrary to prior expectation that hotter was better.If confirmed by subsequent research, this would be good news because in a working chip the switching temperature would be created by the voltage and duration of the electric jolt. Efficient switching at lower temperatures would require less electricity and make RRAM more energy efficient and extend battery life when used as the memory in mobile devices.Much work remains to be done to make RRAM memory practical but this research provides the test bed to vary conditions systematically instead of relying on hit-and-miss hunches. “Now we can use voltage and temperature as design inputs in a predictive manner and that is going to enable us to design a better memory device,” Wang said.Reference:MT16JTF51264AZ-1G6M1SDUS5EB-001GMD2202-D192  

Use of copper as a fluorescent material allows for the manufacture of inexpensive and environmentally compatible organic light-emitting diodes (OLEDs). Thermally activated delayed fuorescence (TADF) ensures high light yield. Scientists of Karlsruhe Institute of Technology (KIT), CYNORA, and the University of St Andrews have now measured the underlying quantum mechanics phenomenon of intersystem crossing in a copper complex. The results of this fundamental work are reported in the Science Advances journal and contribute to enhancing the energy efficiency of OLEDs.  Organic light-emitting diodes are deemed tomorrow's source of light. They homogeneously emit light in all observation directions and produce brilliant colors and high contrasts. As it is also possible to manufacture transparent and flexible OLEDs, new application and design options result, such as flat light sources on window panes or displays that can be rolled up. OLEDs consist of ultra-thin layers of organic materials, which serve as emitter and are located between two electrodes. When voltage is applied, electrons from the cathode and holes (positive charges) from the anode are injected into the emitter, where they form electron-hole pairs. These so-called excitons are quasiparticles in the excited state. When they decay into their initial state again, they release energy.Excitons may assume two different states: Singlet excitons decay immediately and emit light, whereas triplet excitons release their energy in the form of heat. Usually, 25 percent singlets and 75 percent triplets are encountered in OLEDs. To enhance energy efficiency of an OLED, also triplet excitons have to be used to generate light. In conventional light-emitting diodes heavy metals, such as iridium and platinum, are added for this purpose. But these materials are expensive, have a limited availability, and require complex OLED production methods.It is cheaper and environmentally more compatible to use copper complexes as emitter materials. Thermally activated delayed fluorescence (TADF) ensures high light yields and, hence, high efficiency: Triplet excitons are transformed into singlet excitons which then emit photons. TADF is based on the quantum mechanics phenomenon of intersystem crossing (ISC), a transition from one electronic excitation state to another one of changed multiplicity, i.e. from singlet to triplet or vice versa. In organic molecules, this process is determined by spin-orbit coupling. This is the interaction of the orbital angular momentum of an electron in an atom with the spin of the electron. In this way, all excitons, triplets and singlets, can be used for the generation of light. With TADF, copper luminescent material reaches an efficiency of 100 percent.Stefan Bräse and Larissa Bergmann of KIT's Institute of Organic Chemistry (IOC), in cooperation with researchers of the OLED technology company CYNORA and the University of St Andrews, United Kingdom, for the first time measured the speed of intersystem crossing in a highly luminescent, thermally activated delayed fluorescence copper(I) complex in the solid state. The results are reported in the Science Advances journal. The scientists determined a time constant of intersystem crossing from singlet to triplet of 27 picoseconds (27 trillionths of a second). The reverse process – reverse intersystem crossing – from triplet to singlet is slower and leads to a TADF lasting for an average of 11.5 microseconds. These measurements improve the understanding of mechanisms leading to TADF and facilitate the specific development of TADF materials for energy-efficient OLEDs.Reference:KY59-0202NYKY59-S101D2LCD-S301C31TR 

Using state-of-the-art theoretical methods, UCSB researchers have identified a specific type of defect in the atomic structure of a light-emitting diode (LED) that results in less efficient performance. The characterization of these point defects could result in the fabrication of even more efficient, longer lasting LED lighting."Techniques are available to assess whether such defects are present in the LED materials and they can be used to improve the quality of the material," said materials professor Chris Van de Walle, whose research group carried out the work.In the world of high-efficiency solid-state lighting, not all LEDs are alike. As the technology is utilized in a more diverse array of applications—including search and rescue, water purification and safety illumination, in addition to their many residential, industrial and decorative uses—reliability and efficiency are top priorities. Performance, in turn, is heavily reliant on the quality of the semiconductor material at the atomic level."In an LED, electrons are injected from one side, holes from the other," explained Van de Walle. As they travel across the crystal lattice of the semiconductor—in this case gallium-nitride-based material—the meeting of electrons and holes (the absence of electrons) is what is responsible for the light that is emitted by the diode: As electron meets hole, it transitions to a lower state of energy, releasing a photon along the way.Occasionally, however, the charge carriers meet and do not emit light, resulting in the so-called Shockley-Read-Hall (SRH) recombination. According to the researchers, the charge carriers are captured at defects in the lattice where they combine, but without emitting light.The defects identified involve complexes of gallium vacancies with oxygen and hydrogen. "These defects had been previously observed in nitride semiconductors, but until now, their detrimental effects were not understood," explained lead author Cyrus Dreyer, who performed many of the calculations on the paper."It was the combination of the intuition that we have developed over many years of studying point defects with these new theoretical capabilities that enabled this breakthrough," said Van de Walle, who credits co-author Audrius Alkauskas with the development of a theoretical formalism necessary to calculate the rate at which defects capture electrons and holes.The method lends itself to future work identifying other defects and mechanisms by which SRH recombination occurs, said Van de Walle."These gallium vacancy complexes are surely not the only defects that are detrimental," he said. "Now that we have the methodology in place, we are actively investigating other potential defects to assess their impact on nonradiative recombination."Reference:KY59-LM324MMKY59- LM2710KY59- LM3080