Chip circuit for light could be applied to quantum computations

Phys.org  January 3, 2023 While substantial progress has been made, separately, towards ultra-low loss chip-scale photonic circuits and high brightness single-photon sources, integration of these technologies has remained elusive. An international team of researchers (USA – National Institute of Standards and Technology, University of Maryland, research org., MIT, UC Santa Barbara, industry, Brazil, South Korea) integrated a quantum emitter single-photon source with a wafer-scale, ultra-low loss silicon nitride photonic circuit to demonstrate triggered and pure single-photon emission into a Si3N4 photonic circuit with ≈ 1 dB/m propagation loss at a wavelength of ≈ 930 nm. They observed resonance fluorescence in the strong drive regime, showing promise […]

The magneto-optic modulator

EurekAlert  September 16, 2022 Superconducting microprocessors and quantum computers promise to revolutionize computation, but ultra-cold components must interface with ambient temperature systems. An international team of researchers (USA – UC Santa Barbara, industry, Italy, UK, Japan) has built a device that translates electrical input into pulses of light. An electric current creates a magnetic field that changes the refractive index of a synthetic garnet making it possible to tune the amplitude of the light that circulates in a micro-ring resonator. This creates bright and dark pulses that carry information through the fiberoptic cable. The modulator operates at wavelengths of 1,550 […]

Researchers create a magnet made of one molecule

Phys.org  April 13, 2022 Single-molecule magnets (SMMs) are molecules that can retain magnetic polarization in the absence of an external magnetic field and embody the ultimate size limit for spin-based information storage and processing. An international team of researchers (USA – Michigan State University, UK) synthesized two bismuth-cluster-bridged lanthanide complexes via a solution organometallic approach. The neutral heterometallocubane core features lanthanide centers that are bridged by a rare Bi66− Zintl ion, which supports strong ferromagnetic interactions between lanthanides. This afforded the rare observation of magnetic blocking and open hysteresis loops for superexchange-coupled SMMs comprising solely lanthanide ions. The small scale […]

A complete platform for quantum computing

Phys.org  August 13, 2021 A promising and potentially scalable hardware platforms and computational protocols is to combine a photonic platform with measurement-induced quantum information processing. Gate operations can be implemented through optical measurements on a cluster state. Researchers in Denmark designed and demonstrated the deterministic implementation of a multi-mode set of measurement-induced quantum gates in a large two-dimensional optical cluster state using phase-controlled continuous-variable quadrature measurements. Each gate is programmed into the phases of high-efficiency quadrature measurements, which execute the transformations by teleportation through the cluster state. They executed a small quantum circuit consisting of 10 single-mode gates and 2 […]

In leap for quantum computing, silicon quantum bits establish a long-distance relationship

EurekAlert  December 25, 2019 Silicon spin qubits have several advantages over superconducting qubits – they retain their quantum state longer than competing qubit technologies and they could be manufactured at low cost. A team of researchers in the US (Princeton University, industry) connected the qubits via a “wire” which is a narrow cavity containing a photon that picks up the message from one qubit and transmits it to the next qubit. The two qubits were located about half a centimeter apart. The team succeeded in tuning both qubits independently of each other while still coupling them to the photon. An […]

An Optimist’s View of the 4 Challenges to Quantum Computing

IEEE Spectrum  March 22, 2019 According to some experts quantum computing will never materialize as it will require control over an exponentially large number of quantum states, and that this amount of control is too difficult to achieve. According to Intel there are four key challenges that could keep quantum computing from becoming a reality – Qubit Quality, Error Correction, Qubit Control, Too Many Wires. Researches at Intel are working to tackle each of these challenges. But if solved, we could create a commercially relevant quantum computer in about 10-12 years… read more.

Computer program developed to find ‘leakage’ in quantum computers

Science Daily  March 19, 2019 Researchers in the UK used the dimension witnessing approach to show that in program making use of the permitted ‘single qubit’ instructions, unwanted states were being accessed in the transmon circuit components. Their quantum computer program detects the presence of ‘leakage’, where information being processed by a quantum computer escapes from the states of 0 and 1. Most quantum computing hardware platforms suffer from this issue. They verified experimental data from its application on a publicly accessible machine, which shows that undesirable states are affecting certain computations. Even a miniscule leakage accumulating over many millions […]

Current noises of Majorana fermions

Phys.org  July 23, 2018 To detect Majorana fermions researchers in China used non-equilibrium Green’s function method, analyzed the current across a topological Josephson junction and related current noises, revealing the relation between the existence of Majorana fermions and non-equilibrium current noise. In condensed matter physics, zero-energy Majorana fermions obey non-abelian statistics, and can be used in fault-tolerant topological quantum computation… read more. TECHNICAL ARTICLE 

The right squeeze for quantum computing

Phys.org  June 01, 2018 Inherent properties of photons in light are used for encoding information as quantum bits into a light beam by digitizing patterns of the electromagnetic field. “Squeezing” light is used to reduce errors from light waves during quantum computation. Researchers in Japan have developed a theoretical model that uses both the properties of quantum bits and the modes of the electromagnetic field in which they exist. The approach involves squeezing light by removing error-prone quantum bits when quantum bits cluster together. According to the researchers this model is 10 billion times more tolerant to errors than current […]