Phys.org February 28, 2024 Due to the current technological limitations understanding and controlling engineered quantum systems is not always possible. An international team of researchers (Australia, Switzerland, UK, Germany, France, USA – Perdue University) has developed a programmable waveguide array in which the Hamiltonian terms can be individually electro-optically tuned to implement various Hamiltonian continuous-time evolutions on a single device. They used a single array with 11 waveguides in lithium niobate, controlled via 22 electrodes, to perform a range of experiments that realized the Su-Schriffer-Heeger model, the Aubrey-Andre model, and Anderson localization, which is equivalent to over 2500 static devices. […]
Tag Archives: Quantum computer
New analog quantum computers to solve previously unsolvable problems
Phys.org January 30, 2023 Tuning a material to the cusp between two distinct ground states can produce physical properties that are unlike those in either of the neighbouring phases. A tunable array of coupled qubits should have an appropriately rich phase diagram but realizing such a system with either tunnel-coupled semiconductor quantum dots or metal nanostructures has proven difficult. The challenge for scaling up to clusters or lattices is to ensure that each element behaves essentially identically and that the coupling between elements is uniform, while also maintaining tunability of the interactions. Advances in the fabrication and control of quantum […]
Building a silicon quantum computer chip atom by atom (w/video)
Nanowerk January 12, 2022 Until now, implanting atoms in silicon has been a haphazard process, where a silicon chip gets showered with phosphorus which implant in a random pattern. An international team of researchers (Australia, Germany) has developed a technique to place them in an orderly array, similar to the transistors in conventional semiconductors computer chips. They embedded phosphorus ions, precisely counting each one, in a silicon substrate creating a qubit using advanced technology developed for sensitive x-ray detectors and a special atomic force microscope. They drilled a tiny hole in the cantilever, so that when it was showered with phosphorus […]
To capture single photons, researchers create an interference ‘wall’
Phys.org December 3, 2021 Creating entangled photons can be a difficult task requiring a complicated setup as non-classical kinds of light have a small number of photons. In a new scheme researchers at the University of Chicago used two different sources to simultaneously emit photons into a cavity that has an extremely weak nonlinearity. With careful tuning, these sources then cancel each other out with destructive interference—creating a “wall” that blocks photons—once the selected number of photons are captured in the cavity. The basic mechanism can also be applied to all electromagnetic radiation. It can be used to generate and […]
Researchers confront major hurdle in quantum computing
Phys.org May 5, 2021 To realize the full potential of quantum computing high-fidelity information transfer mechanisms are required for quantum error correction and efficient algorithms – and that presents a major experimental challenge. A team of researchers in the US (University of Rochester, Virginia Tech, Purdue University) demonstrated adiabatic quantum state transfer (AQT) which is not affected by pulse errors and noise. They exploited entanglement even when the particles are separated by a large distance to transfer one electron’s quantum spin state across a chain of four electrons in semiconductor quantum dots. AQT is robust against pulse errors and noise. […]
Steering light to places it isn’t supposed to go
Phys.org April 28, 2021 The best materials for housing qubits and certain other optically activated objects typically reflect incident light. By stopping externally applied light from reaching its target, this reflectivity presents a challenge for controlling optically integrated devices. Researchers in the Netherlands have demonstrated a way of guiding light along an arbitrary path through a material by patterning the light’s phase. They shone an infrared beam into the edge of a 2D silicon crystal containing a periodic arrangement of air-filled pores. A large fraction of the light was reflected back along the beam, but because of disorder in the […]
Qubits that operate at room temperature
Phys.org March 17, 2020 Defect-based quantum systems are often complicated by charge-state instabilities and interference by phonons, which can diminish spin-initialization fidelities and limit room-temperature operation. An international team of researchers (Hungary, Sweden, USA – Argonne National Laboratory, University of Chicago, IBM, Russia) identified a pathway around these drawbacks by showing that an engineered quantum well can stabilize the charge state of a qubit. They constructed a model for previously unattributed point defect centers in silicon carbide as a near-stacking fault axial divacancy and show how this model explains these defects’ robustness against photoionization and room temperature stability. These results […]
A decade of Physics World breakthroughs: 2009 – the first quantum computer
Physics World November 29, 2019 Physics World journalists look back at the past decade of winners and explore how research in that field has moved on. Here they examine the 2009 breakthrough for the first “quantum computer”. In August 2009, a NIST team unveiled the first small-scale device that could be described as a quantum computer building up to the breakthrough where the team had used ultracold ions to demonstrate separately all of the steps needed for quantum computation; initializing the qubits; storing them in ions; performing a logic operation on one or two qubits; transferring the information between different […]
This New Chip Could Bridge The Gap Between Classical And Quantum Computing
Science Alert September 28, 2019 An international team of researchers (USA – Purdue University, Japan) has developed hardware for a ‘probabilistic computer’ which solves quantum problems using a p-bit which can only be a 1 or a 0, but they can switch between those two states very quickly and p-bits work at room temperature. By carefully controlling these fluctuations, scientists can tackle calculations of a kind that are generally considered to be quantum computing problems. They modified MRAM device to present a proof-of-concept experiment for probabilistic computing. Factorization of integers up to 945 was demonstrated using eight correlated p-bits, and […]
IBM Quantum Computer Roadmap
Next Big Future March 5, 2019 IBM has published a roadmap for improving quantum computers based on a “quantum volume” which is an architecture-neutral metric. It measures the useful amount of quantum computing done by a device in space and time. The results on the IBM Q System One indicate its performance is just over the threshold for 16. IBM roadmap is to double quantum volume every year. IBM wants to improve error rates 100 times from 1% to 0.01%. They plan to do this by increasing coherence times from 0.5 milliseconds to 1-5 milliseconds. The hope is to achieve quantum […]