quantum computer tagged posts

An IBM cryostat wired for a 50 qubit system. Credit: IBM

IBM has announced a milestone in its race against Google and other big tech firms to build a powerful quantum computer. Dario Gil, who leads IBM’s quantum computing and artificial intelligence research division, said it’s scientists have successfully built and measured a processor prototype with 50 qubits. Gil says it’s the first time any company has built a quantum computer at this scale.

This new processor expands upon the 20 qubit architecture and will be made available in the next generation IBM Q systems. Clients will have online access to the computing power of the first IBM Q systems by the end of 2017, with a series of planned upgrades during 2018...

1. Flow Ambiguity: A Path Towards Classically Driven Blind Quantum Computation. Physical Review X, 2017; 7 (3) DOI: 10.1103/PhysRevX.7.031004
2. Illustration of an exemplary run of Protocol 1

Researchers suggest you could operate a quantum computer in the cloud without revealing your data or the program you’re running. Here’s the scenario: you have sensitive data and a problem that only a quantum computer can solve. You have no quantum devices yourself. You could buy time on a quantum computer, but you don’t want to give away your secrets. What can you do? Writing in Physical Review X on 11 July, researchers in Singapore and Australia propose a way you could use a quantum computer securely, even over the internet. The technique could hide both your data and program from the computer itself...

A cloud of cold atoms is illuminated with red signal light and blue coupling light. The light pulses are superimposed on dichroic mirrors (DM). With wave plates (WP), a polarizing beam splitter (PBS), and avalanche photodiodes (APD) the polarization of the transmitted signal light is determined. Credit: MPQ, Quantum Dynamics Division

MPQ scientists take an important step towards a logical quantum gate for photons. Commonly, a typical quantum computer is considered to be based on a network of quantum particles that serve for storing, encoding and processing quantum information. In analogy to the case of a classical computer a quantum logic gate that assigns output signals to input signals in a deterministic way would be an essential building block...

By evaporating indium gallium arsenide onto a gallium arsenide substrate TUM physicists created nanometer-scale hills, so-called quantum dots. An electron trapped in one of these quantum dots can be used to store information. Hitherto unknown memory loss mechanisms could be switched off by applying a magnetic field. Credit: Fabian Flassig / TUM

Magnetic field helps qubit electrons store information longer. Physicists have tracked down semiconductor nanostructure mechanisms that can result in the loss of stored information – and halted the amnesia using an external magnetic field. The new nanostructures comprise common semiconductor materials compatible with standard manufacturing processes.

In principle, there are various possibilities of implementing qubits: photons are an option equally ...