Quantum computing tagged posts

Regime of a single 1D wire subband filled. Credit: Dr Maria Moreno

Researchers have observed quantum effects in electrons by squeezing them into one-dimensional ‘quantum wires’ and observing the interactions between them. The results could be used to aid in the development of quantum technologies, including quantum computing. Squeezing electrons into a one-dimensional ‘quantum wire’ amplifies their quantum nature to the point that it can be seen, by measuring at what energy and wavelength (or momentum) electrons can be injected into the wire.

“…for electrons in a quantum wire – they repel each other and cannot get past, so if one electron enters or leaves, it excites a compressive wave like the people in the train,” trying to leave a carriage, said Maria Moreno, also from the Cavendish Lab...

Artistic depiction of the generation of three correlated photons from quantum vacuum. Credit: Antti Paraoanu

Microwaves created at near 0K provide uniquely correlated and controllable states. Researchers at Aalto University have demonstrated the suitability of microwave signals in coding of information for quantum computing. Previous development of the field has been focusing on optical systems. They used a microwave resonator based on extremely sensitive measurement devices, ie superconductive quantum interference devices (SQUIDs). The resonator was cooled down and kept near absolute zero, where thermal motion freezes. This state corresponds to perfect darkness where no photon, a particle of electromagnetic radiation eg visible light or microwaves, is present.

However, in this state (quan...

Researchers from MIT and MIT Lincoln Laboratory report an important step toward practical quantum computers, with a paper describing a prototype chip that can trap ions in an electric field and, with built-in optics, direct laser light toward each of them.

Built-in optics could enable chips that use trapped ions as quantum bits. Although quantum systems with as many as 12 qubits have been demonstrated in the lab, building quantum computers complex enough to perform useful computations will require miniaturizing qubit technology, much the way the miniaturization of transistors enabled modern computers.

Trapped ions are probably the most widely studied qubit technology, but they’ve historically required a large and complex hardware apparatus...

Multiple reflections like in a drop of paint

Inside a drop of paint, light is scattered so often that it seems impossible to demonstrate quantum effects. But despite the thousands of possible paths the light can take, researchers of the Uni of Twente now show that there are just 2 exits. Depending on the light pattern that enters the paint, 2 photons always come out through the same exit, or through different ones – as though they avoid each other.

Most of the experiments showing that light sometimes behaves like a wave and sometimes like a particle, are as simple as possible: a physics textbook example is Young’s two slit experiment. The number of possible light paths is limited, but even at this level, the experiments strongly challenge our intuition...