Phys.org January 4, 2022 Recent breakthroughs in quantum computation with superconducting circuits trigger a demand for quantum communication channels between spatially separated superconducting processors operating at microwave frequencies. An international team of researchers (Germany, Austria) demonstrated the unconditional quantum teleportation of propagating coherent microwave states by exploiting two-mode squeezing and analog feedforward over a macroscopic distance of d = 0.42 m. They achieved a teleportation fidelity of F = 0.689 ± 0.004, exceeding the asymptotic no-cloning threshold. Thus, the quantum nature of the teleported states is preserved, opening the avenue toward unconditional security in microwave quantum communication. As their principal teleportation […]
Tag Archives: Quantum technology
A-list candidate for fault-free quantum computing delivers surprise
Science Daily December 22, 2021 Spin-triplet pairing is important because it can host topological states and majorana fermions relevant for quantum computation. Because spin-triplet pairing is usually mediated by ferromagnetic (FM) spin fluctuations, uranium-based materials near an FM instability are ideal candidates for realizing spin-triplet superconductivity. UTe2 has been identified as a candidate for a chiral spin-triplet topological superconductor near an FM instability, although it also has antiferromagnetic (AF) spin fluctuations. A team of researchers in the US (Rice University, Florida State University, Oak Ridge National Laboratory, UC San Diego, Arizona State University) used inelastic neutron scattering (INS) to show […]
Scientists document the presence of quantum spin liquids, a never-before-seen state of matter
Phys.org December 2, 2021 To reproduce the microscopic physics found in condensed matter systems an international team of researchers (USA – Harvard University, MIT, Austria) used a simulator that allows the researchers to create programmable shapes like squares, honeycombs, or triangular lattices to engineer different interactions and entanglements between ultracold atoms. Quantum spin liquids display none of that magnetic order because, essentially, there is a third spin added, turning the checker box pattern to a triangular pattern making it a “frustrated” magnet where the electron spins can’t stabilize in a single direction. The researchers used the simulator to create their […]
Researchers propose a simpler design for quantum computers
Phys.org November 29, 2021 It is challenging to construct large numbers of gates for photons and connect them in a reliable fashion to perform complex calculations. Researchers at Stanford University have proposed a scalable architecture for a photonic quantum computer using readily available components – a fiber optic cable, a beam splitter, a pair of optical switches and an optical cavity, and the size of the machine doesn’t increase with the size of the quantum program you want to run. The design consists of two main sections – a storage ring and a scattering unit. The storage ring is a fiber […]
Shrinking qubits for quantum computing with 2D materials
Nanowerk December 1, 2021 The capacitor electrodes that comprise the qubits in quantum computers must be large to avoid lossy dielectrics. This hinders scaling degrading individual qubit addressability and limiting the spatial density of qubits. An international team of researchers (USA – Columbia University, Raytheon BBN Technologies, Japan) took advantage of the unique properties of van der Waals (vdW) materials to reduce the qubit area by >1000 times while preserving the capacitance while maintaining quantum coherence. The qubits combine conventional aluminum-based Josephson junctions with parallel-plate capacitors composed of crystalline layers of superconducting niobium diselenide and insulating hexagonal boron nitride. The […]
Tiny chip provides a big boost in precision optics
Phys.org November 12, 2021 Based on a theory of weak value amplification with waveguides, a team of researchers in the US (University of Rochester, industry, Chapman University) has packaged an experimental way of amplifying interferometric signals—without a corresponding increase in noise —on a 1 mm by 1 mm integrated photonic chip. Weak value amplification is based on the quantum mechanics of light, and basically involves directing only certain photons that contain the information needed, to a detector. They distilled all of this and put it into a photonic chip. The device removes that limitation of traditional interferometers by reaching the […]
How a novel radio frequency control system enhances quantum computers
Phys.org November 9, 2021 Researchers at the Lawrence Berkeley National Laboratory have demonstrated a new way to control qubits by substituting the larger, more costly traditional RF control systems with smaller interactive mixing modules. The modular system has high -reliability, delivering high-resolution, low-noise RF signals needed to manipulate and measure the superconducting qubit at room temperature. To do so, they shifted the qubit manipulation and measurement signal frequency between the electronics baseband and the quantum system. According to the researchers their system could be expanded to other quantum information science platforms, and RF mixing can be expanded to higher frequencies. […]
Researchers reach quantum networking milestone in real-world environment
Phys.org October 6, 2021 A team of researchers in the US (Oak Ridge National Laboratory, Stanford University, Purdue University) implemented flex-grid entanglement distribution in a deployed network connecting nodes in three distinct campus buildings time synchronizing via the Global Positioning System. They quantify the quality of the distributed polarization entanglement via log-negativity, which offers a generic metric of link performance in entangled bits per second. After demonstrating successful entanglement distribution for two allocations of their eight dynamically reconfigurable channels, they realized the first deployed fiber network demonstration of remote state preparation (RSP), a fundamental quantum communications protocol with utility for […]
Implementing a 46-node quantum metropolitan area network
Phys.org September 30, 2021 To achieve a practical quantum network, we need to overcome several challenges including realizing versatile topologies for large scales, simple network maintenance, extendable configuration, and robustness to node failures. To this end, an international team of researchers (China, Germany) developed a field operation of a quantum metropolitan-area network with 46 nodes and showed that all these challenges can be overcome with cutting-edge quantum technologies. They used different topological structures and continuously ran the network for 31 months, by employing standard equipment for network maintenance with an extendable configuration. QKD pairing and key management was done with […]
A new way to control qubits
Phys.org September 22, 2021 A team of researchers in the US (NIST, University of Colorado, Lawrence Livermore National Laboratory, University of Oregon, UT Austin) demonstrated high-fidelity laser-free universal control of two trapped-ion qubits by creating both symmetric and antisymmetric maximally entangled states with fidelities of 1+0−0.0017 and 0.9977+0.0010−0.0013, respectively (68 per cent confidence level), corrected for initialization error. They used a scheme based on radiofrequency magnetic field gradients combined with microwave magnetic fields that is robust against multiple sources of decoherence and usable with essentially any trapped ion species. The scheme has the potential to perform simultaneous entangling operations on […]