A technology group at MIT have put forward the notion that diamonds could provide the basis for efficient and practical quantum computers. This is based on atom-scale defects in diamonds which could be used to store quantum bits and also for the held data such a contradictory commands like on and off to be read without the risk of the data being altered.
The ‘on’ and ‘off’ commands, at the atomic scale and in differing locations, are important since quantum computers use quantum bits, which can be in superpositions of states. Superposition moves computing from binary constraints and theoretically delivers more computing power. A quantum computer works with particles (termed ‘qubits’) that can be in superposition.
With a binary computer (as with all modern computer devices, such as the one you’re reading this article on work, on a series of ‘0’ and ‘1’ states for individual bits; a quantum computer can have bits at ‘0’ or ‘1’ at the same time). Through this quantum computers could harness the power of atoms and molecules to perform memory and processing tasks.
How do quantum computers work?
Quantum computing is receiving major investment because such devices would use elements of quantum mechanics to complete previously impossible calculations in a fraction of a second. This is possible through the unpredictable behavior of ‘qubits’,
Diamonds and silicon
The use of diamonds to advance the quantum mechanics needed for supercomputers is fine in theory; however, common defects in diamonds appear to emit a broad range of light. The issue with this is that it renders the data reading too inaccurate. This problem appears to have been overcome by scientists who can reduce the level of inaccuracy down to a level that does not impair performance. This is achieved by adding silicon into the defect. The outcome of this addition of the silicon leads to the emission of light which is far narrower, allowing the data to be read efficiently and in a way where the defect has no significance.
As things stand today, the development of practical quantum computers is at its infancy. However, experiments have been performed in which quantum computational operations have been executed on a very small number of quantum bits. The results suggest we’re heading, albeit haphazardly, towards a future-state quantum computing world.
Why diamond-based quantum computers?
By fitting silicon atoms into a diamond substrate it is possible to use laser-generated photons to shift silicon electrons into their next higher atomic energy state. Once these electrons return to the lower energy state they push out quantized photons that carry information. The information is far more complex than data carried on standard computers due to the frequency, intensity and the polarization of the electron wave. This of course, remains, theoretical.
MIT researchers make silicon-filled diamonds
To enhance diamonds for quantum computing the Massachusetts Institute of Technology researchers created a synthetic diamond just 200 nanometers thick. Using this, Engadget reports, the researchers etched optical cavities into its surface. This functioned to increase the brightness of light emissions. They then used a device called a nanoscale implanter to project silicon ions into the cavities.
The process was enhanced by the bombardment of electron beams to create more cavities to be filled by the silicon. Silicon is a hard and brittle crystalline solid with a blue-gray metallic luster and it is widely used for electronics. It’s also an intrinsic semiconductor, so that, unlike metals, it conducts electron holes and electrons released from atoms by heat.
Through this process, silicon-filled defects were created by blasting the diamond with electron beams (which creates more cavities to be filled by silicon). The beams also heated the diamond in a way that led to the nano-sized holes being moved around, which facilitated the bonding with the silicon.
The process remains a work in progress, and more needs to be done to orientate the defects in optimal locations so that the light emitted allows for maximal data processing. The MIT researchers see the development as the springboard for diamond-based quantum computers.
The research is described in the journal Nature, in a paper titled “Scalable focused ion beam creation of nearly lifetime-limited single quantum emitters in diamond nanostructures.”
