A new five-qubit array from UCSB’s Martinis Group is on the threshold of making a quantum computer technologically feasible to build
A fully functional quantum computer is one of the holy grails of physics. Unlike conventional computers, the quantum version uses qubits (quantum bits), which make direct use of the multiple states of quantum phenomena. When realized, a quantum computer will be millions of times more powerful at certain computations than today’s supercomputers.
A group of UC Santa Barbara physicists has moved one step closer to making a quantum computer a reality by demonstrating a new level of reliability in a five-qubit array. Their findings appear Thursday in the journal Nature.
Quantum computing is anything but simple. It relies on aspects of quantum mechanics such as superposition. This notion holds that any physical object, such as an atom or electron — what quantum computers use to store information — can exist in all of its theoretical states simultaneously. This could take parallel computing to new heights.
“Quantum hardware is very, very unreliable compared to classical hardware,” says Austin Fowler, a staff scientist in the physics department, whose theoretical work inspired the experiments of the Martinis Group. “Even the best state-of-the-art hardware is unreliable. Our paper shows that for the first time reliability has been reached.”
While the Martinis Group has shown logic operations at the threshold, the array must operate below the threshold to provide an acceptable margin of error. “Qubits are faulty, so error correction is necessary,” said graduate student and co-lead author Julian Kelly who worked on the five-qubit array.
“We need to improve and we would like to scale up to larger systems,” said lead author Rami Barends, a postdoctoral fellow with the group. “The intrinsic physics of control and coupling won’t have to change but the engineering around it is going to be a big challenge.”
The unique configuration of the group’s array results from the flexibility of geometry at the superconductive level, which allowed the scientists to create cross-shaped qubits they named Xmons. Superconductivity results when certain materials are cooled to a critical level that removes electrical resistance and eliminates magnetic fields. The team chose to place five Xmons in a single row, with each qubit talking to its nearest neighbor, a simple but effective arrangement.
“Motivated by theoretical work, we started really thinking seriously about what we had to do to move forward,” said John Martinis, a professor in UCSB’s Department of Physics. “It took us a while to figure out how simple it was, and simple, in the end, was really the best.”
“If you want to build a quantum computer, you need a two-dimensional array of such qubits, and the error rate should be below 1 percent,” said Fowler. “If we can get one order of magnitude lower — in the area of 10-3 or 1 in 1,000 for all our gates — our qubits could become commercially viable. But there are more issues that need to be solved. There are more frequencies to worry about and it’s certainly true that it’s more complex. However, the physics is no different.”
According to Martinis, it was Fowler’s surface code that pointed the way, providing an architecture to put the qubits together in a certain way. “All of a sudden, we knew exactly what it was we wanted to build because of the surface code,” Martinis said. “It took a lot of hard work to figure out how to piece the qubits together and control them properly. The amazing thing is that all of our hopes of how well it would work came true.”
Julie Cohen | Eurek Alert!
New record in materials research: 1 terapascals in a laboratory
22.07.2016 | Universität Bayreuth
Mapping electromagnetic waveforms
22.07.2016 | Max-Planck-Institut für Quantenoptik
Munich Physicists have developed a novel electron microscope that can visualize electromagnetic fields oscillating at frequencies of billions of cycles per second.
Temporally varying electromagnetic fields are the driving force behind the whole of electronics. Their polarities can change at mind-bogglingly fast rates, and...
Breakup of continents with two speed: Continents initially stretch very slowly along the future splitting zone, but then move apart very quickly before the onset of rupture. The final speed can be up to 20 times faster than in the first, slow extension phase.phases
Present-day continents were shaped hundreds of millions of years ago as the supercontinent Pangaea broke apart. Derived from Pangaea’s main fragments Gondwana...
Scaffolding and specialised workers help with the delivery – Heidelberg biochemists gain new insights into biogenesis
A type of scaffolding on which specialised workers ply their trade helps in the manufacturing process of the two subunits from which the ribosome – the protein...
Scientists at the Helmholtz Zentrum München have developed a new mass spectrometry imaging method which, for the first time, makes it possible to analyze hundreds of metabolites in fixed tissue samples. Their findings, published in the journal Nature Protocols, explain the new access to metabolic information, which will offer previously unexploited potential for tissue-based research and molecular diagnostics.
In biomedical research, working with tissue samples is indispensable because it permits insights into the biological reality of patients, for example, in...
Chemists at the University of Basel have succeeded in using computer simulations to elucidate transient structures in proteins. In the journal Angewandte Chemie, the researchers set out how computer simulations of details at the atomic level can be used to understand proteins’ modes of action.
Using computational chemistry, it is possible to characterize the motion of individual atoms of a molecule. Today, the latest simulation techniques allow...
15.07.2016 | Event News
15.07.2016 | Event News
11.07.2016 | Event News
22.07.2016 | Information Technology
22.07.2016 | Physics and Astronomy
22.07.2016 | Life Sciences