In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based quantum capacitor, compatible with cryogenic conditions of superconducting circuits, and based on two-dimensional (2D) materials.
When connected to a circuit, this capacitor has the potential to produce stable qubits and also offers other advantages, such as being relatively easier to fabricate than many other known nonlinear cryogenic devices, and being much less sensitive to electromagnetic interference. This research was published in 2D Materials and Applications.
Normal digital computers operate on the basis of a binary code composed of bits with a value of either 0 or 1. In quantum computers, the bits are replaced by qubits, which can be in two states simultaneously, with arbitrary superposition. This significantly boosts their calculation and storage capacity for certain classes of applications. But making qubits is no mean feat: quantum phenomena require highly controlled conditions, including very low temperatures.
To produce stable qubits, one promising approach is to use superconducting circuits, most of which operate on the basis of the Josephson effect. Unfortunately, they are difficult to make and sensitive to perturbing stray magnetic fields. This means the ultimate circuit must be extremely well shielded both thermally and electromagnetically, which precludes compact integration.
At EPFL's LPQM, this idea of a capacitor that's easy to make, less bulky and less prone to interference has been explored. It consists of insulating boron nitride sandwiched between two graphene sheets. Thanks to this sandwich structure and graphene's unusual properties, the incoming charge is not proportional to the voltage that is generated. This nonlinearity is a necessary step in the process of generating quantum bits.
This device could significantly improve the way quantum information is processed but there are also other potential applications too. It could be used to create very nonlinear high-frequency circuits -- all the way up to the terahertz regime -- or for mixers, amplifiers, and ultra strong coupling between photons.
Laboratory of Photonics and Quantum Measurements LPQM (STI/SB)
Source: Nonlinear Graphene Quantum Capacitors for Electro-optics
sina.khorasani | EurekAlert!
Smallest transistor worldwide switches current with a single atom in solid electrolyte
17.08.2018 | Karlsruher Institut für Technologie (KIT)
Protecting the power grid: Advanced plasma switch for more efficient transmission
17.08.2018 | DOE/Princeton Plasma Physics Laboratory
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
17.08.2018 | Physics and Astronomy
17.08.2018 | Information Technology
17.08.2018 | Life Sciences