MIT researchers may have found a way to overcome a key barrier to the advent of super-fast quantum computers, which could be powerful tools for applications such as code breaking.
Ever since Nobel Prize-winning physicist Richard Feynman first proposed the theory of quantum computing more than two decades ago, researchers have been working to build such a device.
One approach involves superconducting devices that, when cooled to temperatures of nearly absolute zero (-459 degrees F, -273 degrees C), can be made to behave like artificial atoms - nanometer-scale "boxes" in which the electrons are forced to exist at specific, discrete energy levels (picture an elevator that can stop at the floors of a building but not in between). But traditional scientific techniques for characterizing - and therefore better understanding - atoms and molecules do not necessarily translate easily to artificial atoms, said William Oliver of MIT Lincoln Laboratory's Analog Device Technology Group and MIT's Research Laboratory for Electronics (RLE).
In the Sept. 4 issue of Nature, Oliver and colleagues have reported a technique that could fill that gap. Oliver's co-authors are lead author David Berns, a graduate student in physics and RLE; Mark Rudner, also a graduate student in physics; Sergio Valenzuela, a research affiliate at MIT's Francis Bitter Magnet Laboratory; Karl Berggren, the Emanuel E. Landsman Career Development Associate Professor in the Department of Electrical Engineering and Computer Science (EECS); Professor Leonid Levitov of physics; and EECS Professor Terry Orlando. The work is a hallmark of the increased collaboration between researchers on the MIT campus and at Lincoln Laboratory.
Characterizing energy levels is fundamental to the understanding and engineering of any atomic-scale device. Ever since Isaac Newton showed that sunlight could be dispersed into a continuous color spectrum, each color representing a different energy, this has been done through analysis of how an atom responds to different frequencies of light and other electromagnetic radiation - a technique known generally as spectroscopy.
But artificial atoms have energy levels that correspond to a very wide swath of frequencies, ranging from tens to hundreds of gigahertz. That makes standard spectroscopy costly and difficult to apply. "The application of frequency spectroscopy over a broad band is not universally straightforward," Oliver said.
The MIT team developed a complementary approach called amplitude spectroscopy that provides a way to characterize quantum entities over extraordinarily broad frequency ranges. This procedure is "particularly relevant for studying the properties of artificial atoms," Oliver said.
Better knowledge of these superconducting structures could hasten the development of a quantum computer. Each artificial atom could function as a "qubit," or quantum bit, which can be in multiple energy states at once. That means it would not be simply a one or a zero (like the electronic switches in a conventional computer) but rather in a sort of hazy combination of both states (it's akin to the famous paradox of Schroedinger's quantum cat, which is considered to be both alive and dead at the same time until an observation is made, simultaneously creating and revealing its true condition). This odd behavior, inherent to the quantum nature of materials at the atomic level, is what gives quantum computing such promise as a paradigm-busting advance.
Amplitude spectroscopy gleans information about a superconducting artificial atom by probing its response to a single, fixed frequency that is strategically chosen to be, as Oliver puts it, "benign." This probe pushes the atom through its energy-state transitions. In fact, the atoms can be made to jump between energy bands at practically unlimited rates by adjusting the amplitude of the fixed-frequency source.
The radiation emitted by the artificial atom in response to this probe exhibits interference patterns. These patterns, which Oliver calls "spectroscopy diamonds" because of their striking geometric regularity, serve as fingerprints of the artificial atom's energy spectrum.
Elizabeth Thomson | EurekAlert!
NASA spacecraft investigate clues in radiation belts
28.03.2017 | NASA/Goddard Space Flight Center
Researchers create artificial materials atom-by-atom
28.03.2017 | Aalto University
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
28.03.2017 | Life Sciences
28.03.2017 | Information Technology
28.03.2017 | Physics and Astronomy