Phys.org May 23, 2023 An international team of researchers (Austria, France) has presented a quantum repeater node based on trapped ions that act as single-photon emitters, quantum memories, and an elementary quantum processor. They demonstrated the node’s ability to establish entanglement across two 25-km-long optical fibers independently, then to swap that entanglement efficiently to extend it over both fibers. The resultant entanglement was established between telecom-wavelength photons at either end of the 50 km channel. Finally, they calculated the system improvements to allow for repeater-node chains to establish stored entanglement over 800 km at hertz rates revealing a near-term path […]
Tag Archives: Communications technology
Mechanical engineering meets electromagnetics to enable future technology
Science Daily February 13, 2023 Reconfigurable electromagnetic devices, specifically reconfigurable antennas, have shown to be integral to the future of communication systems. However, mechanically robust designs that can survive real-world, harsh environment applications and high-power conditions remain rare. Researchers at Pennsylvania State University have developed the general framework for a field of both discrete and continuously mechanically reconfigurable devices by combining compliant mechanisms with electromagnetics. They demonstrated a reconfigurable compliant mechanism antenna which exhibited continuously tunable performance across a broad band of frequencies. Three additional examples were also introduced to showcase the versatility and advanced capabilities of compliant mechanism enabled […]
Satellites may enable better quantum networks
Phys.org February 10, 2023 Satellite-based quantum links have been proposed to extend the network domain for quantum communication. An international team of researchers (USA – Oak Ridge National Laboratory, University of Illinois, Singapore) developed a quantum communication system, suitable for realistic satellite-to-ground communication and executed an entanglement-based quantum key distribution (QKD) protocol achieving quantum bit-error rates (QBERs) below 2% in all bases. They demonstrated low-QBER execution of a higher-dimensional hyperentanglement-based QKD protocol, using photons simultaneously entangled in polarization and time bin, leading to significantly higher secure key rates, at the cost of increased technical complexity and system size. They showed […]
New shield blocks electromagnetic interference while allowing wireless optical signals
Phys.org January 25,2023 An international team of researchers (Sweden, China) experimentally demonstrated, for the first time, a mechanically flexible silver mesh that is visibly transparent, allows high-quality infrared wireless optical communication and efficiently shields electromagnetic interference in the X band portion of the microwave radio region. The Ag mesh/polyethylene (PE) achieved high average EMI shielding effectiveness (SE) of 28.8 dB in the X band with an overall transmittance of 80.9% at 550 nm. With a polydimethylsiloxane (PDMS) coating, the average EMI SE was still up to 26.2 dB and the overall transmittance was increased to 84.5% at 550 nm due […]
High-visibility quantum interference between two independent semiconductor quantum dots achieved
Phys.org December 28, 2022 There has been exciting recent progress in satellite-based quantum communications and quantum repeaters, but a lack of suitable single-photon sources has hampered further advances. The visibility of quantum interference between independent QDs rarely went beyond the classical limit of 50%, and the distances were limited from a few meters to kilometers. An international team of researchers (China, Germany) has shown quantum interference between two single photons from independent QDs separated by a 302 km optical fiber. The single photons were generated from resonantly driven single QDs deterministically coupled to microcavities. Quantum frequency conversions were used to […]
New technique reveals changing shapes of magnetic noise in space and time
Phys.org December 23, 2022 Nitrogen vacancy (NV) centers in diamond can be used to sense magnetic fields with high sensitivity and spatial resolution. Typically, the magnetic field is measured by averaging sequential measurements of single NV centers, or by spatial averaging over ensembles of many NV centers, which provides mean values that contain no nonlocal information about the relationship between two points separated in space or time. A team of researchers in the US (Princeton University, University of Wisconsin) used specially designed diamonds to develop a technique to measure noise in a material by studying correlations and used this information […]
Quantum leap for research into unhackable communications networks
Phys.org November 30, 2022 Quantum steering relaxes the strict technological constraints of Bell nonlocality by reframing it in an asymmetric manner, with a trusted party only on one side. However, tests of quantum steering still require either extremely high-quality entanglement or very low loss. An international team of researchers (UK, Switzerland) constructed a test of quantum steering for qudits harnessing the advantages of high-dimensional entanglement to be simultaneously noise robust and loss tolerant. It was designed for single-detector measurements and was able to close the fair-sampling loophole in a time-efficient manner. They demonstrated quantum steering in up to 53 dimensions, […]
Microlaser chip adds new dimensions to quantum communication
Phys.org November 21, 2022 In quantum communications with qubits, the superposition makes it so a quantum pulse cannot be copied. However, with only two levels of superposition, qubits have limited storage space and low tolerance for interference. An international team of researchers (USA – University of Pennsylvania, Duke University, City University of New York, Spain, Italy) has created a chip that outstrips the security and robustness of existing quantum communications hardware. The device’s four-level qudits enable significant advances in quantum cryptography, raising the maximum secrete key rate for information exchange from 1 bit per pulse to 2 bits per pulse. […]
Researchers present anti-reflective coating that blocks waves of many types
Phys.org July 14, 2022 An international team of researchers (Austria, France) has developed a method that allows the calculation of a tailor-made anti-reflective structure which can be used to design an additional layer to the medium only partially permeable to a wireless signal so that the entire signal can be channeled through the medium without reflections. To determine the anti-reflective structure they sent the waves through the medium and measured exactly in which way these waves are reflected by the material. Using a mathematical technique they calculated the corresponding compensating structure so that the combination of both media allowed the […]
Researchers achieve record entanglement of quantum memories
Phys.org July 7, 2022 To fully use entanglement over long-distance quantum network links it is mandatory to know it is available at the nodes before the entangled state decays. An international team of researchers (Austria, Germany) demonstrated entanglement between two independently trapped single rubidium atoms generated over fibre links with a length up to 33 km. They generated atom–photon entanglement in two nodes located in buildings 400 m line-of-sight apart and to overcome high-attenuation losses in the fibres converted the photons to telecom wavelength using polarization-preserving quantum frequency conversion. The long fibres guided the photons to a Bell-state measurement setup in which […]