Modern computing is digital, a series of 1s and 0s that, once combined, create powerful information processing systems. The system is so simple – on or off, yes or no – that it almost seems dumb. It is that very simplicity that gives digital computing its power. It works very well.
But we have a problem. Silicon circuits are getting so small that they will soon be bumping up against a fundamental physical limit.
“We know very well that, as the miniaturisation of computers continues, at some point the carriers of information will have a size that approaches that of atoms,” warns Nicolas Cerf, coordinator of the Covaqial project. “As classical physics becomes inapplicable, we will have to look at quantum mechanics for our future information processing systems.”
And that is exactly what quantum scientists have been doing for the last 20 years. Essentially, they have been attempting to reproduce the classical, digital, computer of 1s and 0s in the microscopic world by using particles to carry information as quantum bits, or qubits. Up to now, it really was the only game in quantum town.Logic, but not as we know it
“In classical computing, there have been attempts to create an analogue logic, but no major success,” notes Cerf. “But it turns out, for a variety of reasons, that using an analogue approach, like continuous variables, might work very well in quantum computing. We felt it was a promising approach, so that is why we started up Covaqial.”
Unlike qubits, where one atom or particle carries the information, continuous variables (CV) use an ensemble of atoms or photons to carry the information – the first with matter and the second with light.
Both digital and analogue approaches to quantum information science use the peculiar properties of quantum particles as the ‘signifier’ of the information carried, such as the spin of a single electron or the polarisation of a photon for qubits, or the analogue properties of a group of electrons or photons for CV.
“It is the collective property of this group of electrons, or photons, that becomes the information carrier in CV. When you have this many particles you can call it continuous even though there are many very small steps in the information-encoding variable,” relates Cerf.
The upshot, though, and what makes CV interesting, is that it is much easier to manipulate, control and experiment with than individual particles. Quantum teleportation using qubits, for example, was described in the early 1990s and proved experimentally five years later. In contrast, teleportation with CV was proved experimentally just one year after it was theorised. All because CVs are much easier to use.Cat out of the bag
“We achieved the first major result after less than one year. It was an experiment demonstrating quantum memory,” explains Cerf. “It’s like classical memory, so it is really a prerequisite for the field.”
The team demonstrated memory for a light pulse stored in an atomic ‘ensemble’ during one millisecond using CV. It might not sound like much, but remember light travels several hundred kilometres in that time. Even if looped in an optical fibre, the energy is so delicate that it would disappear in well under a millisecond. They did this at room temperature, whereas atomic qubits generally need to be super-cooled.
The second result created an optical ‘Schroedinger’s cat’. Schrödinger’s cat was a thought experiment that illustrated how objects can have two distinct states at the same time, in this case a dead cat and a live cat.
Covaqial created a light pulse – an ensemble of photons – simultaneously in two states. “It is very important for the development of a quantum repeater, which will allow quantum communications to extend to much further distances,” Cerf reveals.
Finally, for the first time ever, an experiment demonstrated interspecies quantum teleportation. Teleportation occurs where the state of one particle is moved onto another particle. “It had been done before with photons or atoms, but this is the first time it worked from photons to atoms. These were our most impressive results, but we had many more,” notes Cerf.
As a result of their work, CVs are now a hot topic in quantum information processing, and Covaqial propelled Europe to leadership in the field. Now, the team will continue their work in a new European Commission project, COMPAS, starting in a few months.
“Strictly speaking, Covaqial was about quantum communication, but all the results will be essential for the development of quantum computing,” explains Cerf. “COMPAS will attack directly the challenges of quantum information processing using CVs.”
Further helping to usher in the era of the analogue quantum computer.
Christian Nielsen | alfa
Fraunhofer FIT joins Facebook's Telecom Infra Project
25.10.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT
Stanford researchers create new special-purpose computer that may someday save us billions
21.10.2016 | Stanford University
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
25.10.2016 | Earth Sciences
25.10.2016 | Life Sciences
25.10.2016 | Earth Sciences