Phys.org March 2, 2021 In the emerging field of quantum networking, the need for effective resource provisioning is particularly acute, given the generally lower power levels, higher sensitivity to loss, and inapplicability of optical detection and retransmission. A team of researchers in the US (Purdue University, Oak Ridge National Laboratory) has demonstrated reconfigurable distribution of quantum entanglement in a four-user tabletop network. By adaptively partitioning bandwidth with a single wavelength-selective switch, they successfully equalized two-party coincidence rates that initially differed by over two orders of magnitude. Their scalable approach introduces loss that is fixed with the number of users, offering […]
Tag Archives: Quantum internet
Adding or subtracting single quanta of sound
Science Daily January 25, 2021 An international team of researchers (UK, Denmark, Australia) injected laser light into a crystalline microresonator that supports both the light and the high-frequency sound waves. The two types of waves coupled to one another via an electromagnetic interaction creates light at a new frequency. To subtract a single phonon, the team detected a single photon that has been up shifted in frequency. Detecting a single photon indicates that a subtracted single phonon. When the experiment is performed at a finite temperature, the sound field has random fluctuations from thermal noise. Counterintuitively, when you subtract a […]
Researchers achieve sustained, high-fidelity quantum teleportation
Phys.org December 29, 2020 An international team of researchers (USA – Caltech, Fermi National Accelerator Laboratory, industry, Harvard University, Canada) used fiber-coupled devices, including state-of-the-art low-noise superconducting nanowire single-photon detectors and off-the-shelf optics to achieve conditional quantum teleportation of time-bin qubits at the telecommunication wavelength of 1536.5 nm. They measured teleportation fidelities that are consistent with an analytical model of their system, which includes realistic imperfections. To demonstrate the compatibility of the setup with deployed quantum networks, they teleported qubits over 22 km of single-mode fiber while transmitting qubits over an additional 22 km of fiber. Their systems, which are […]
Trapped ytterbium ions could form backbone of a quantum internet, say researchers
Phys.org April 13, 2020 An international team of researchers (USA – University of Colorado, NIST, Caltech, Australia, Singapore) fabricated a periodic, nano-patterned 10 micron-long cavity with the ion at its centre. Light bounces back and forth many times in the cavity, greatly increasing the chance of the light interacting with the ion. The researchers then manipulated their ion qubit using laser and microwave pulses. The result is the emission of a photon that is entangled with the qubit – a photon that itself is a flying qubit of quantum information. More than 99% of the time, they found that this […]
Practical anonymous communication protocol developed for quantum networks
Phys.org August 21, 2019 In the protocol developed by an international team of researchers (UK, USA – MIT, France) the player who wants to send a message anonymously notifies the receiver. Then, in each round of the protocol, an untrusted source creates an entangled quantum state called the Greenberger-Horne-Zeilinger (GHZ) state and distributes it between the players. Each player can either check if the state is actually the GHZ state by running a verification test or use the state for anonymous quantum communication. If test fails, there is possible breach, the misbehaving source is caught. If they use the state […]
Tunable diamond string may hold key to quantum memory
Science Daily May 22, 2018 The uncontrolled interaction of a quantum system with its environment is detrimental for quantum coherence. An international team of researchers (USA – Harvard University, Sandia National Laboratory, UK) used a nano-electro-mechanical system to mitigate the effect of thermal phonons on a spin qubit, the silicon vacancy color center, without changing the system temperature. By controlling the strain environment of the colour centre, they tuned its electronic levels to probe, control, and eventually suppress the interaction of its spin with the thermal bath. Strain control provided both large tunability of the optical transitions and significantly improved […]
The quantum internet has arrived (and it hasn’t)
Nature February 14, 2018 Researchers in the Netherlands argue that they could use quantum mechanics to do much more, by harnessing nature’s uncanny ability to link or entangle distant objects, and teleporting information between them. They have already started to build the first genuine quantum network, which will link four cities in the Netherlands. The project, set to be finished in 2020, could be the quantum version of ARPANET. The lead scientist is also coordinating a larger European project, called the Quantum Internet Alliance, which aims to expand the Dutch experiment to a continental scale… read more