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According to scientists at the US Army Research Laboratory. In the USA, quantum computer circuits that will no longer require extremely cold temperatures to operate soon may become reality in about 10 years.
For many years, solid-state quantum technology operating at room temperature seemed to be overstated. Although the use of transparent crystals with optical nonlinearities has evolved as the most powerful way to achieve this milestone, the likelihood that such a system will remain a mystery.
Now, the validity of this method has been officially confirmed by Army investigators. Dr. Kurt Jacobs of the Army Research Laboratory of the US Army Combat Capability Development Command. In collaboration with Dr. Mikkel Heuck and Professor Dirk Englund of the Massachusetts Institute of Technology (MIT), he became the first researcher to show the feasibility of a quantum logic gate containing optical elements crystals and photonic circuits. .
If future devices using quantum technologies require cooling to very cold temperatures, then this will make them expensive, bulky, and energy-hungry. Our research aims to develop future photonic circuits that can manipulate the entanglement required for quantum devices at room temperature..
Dr. Mikkel Heuck, Massachusetts Institute of Technology
Quantum technology provides a variety of future developments in remote sensing, communications, and computing.
Conventional classic computers operate with fully determined data to accomplish any type of job. This data is held in multiple bits, with each bit turned on or off. When an input specified by a number of bits is fed to a traditional computer, the computer will process this input to generate a response, which is also specified as a number of bits. An entry will only be processed by a traditional computer at any given time.
On the other hand, quantum computers preserve data in qubits that can exist in an unusual state, where they exist in both an on and off state simultaneously. This allows a quantum computer to analyze the responses to several inputs simultaneously.
While the quantum computer cannot produce results for all of the responses at the same time, it can generate results for the associations between these responses, allowing you to solve certain problems relatively faster than the traditional computer.
Unfortunately, one of the main disadvantages of quantum systems is the delicacy of the special states of the qubits. Most potential hardware for quantum technology must be kept in very cold temperatures (close to 0 K) so that strange states are not damaged during interaction with the computer setup.
Any interaction that has a qubit with anything else in its environment will begin to distort its quantum state. For example, if the environment is a particulate gas, keeping it very cold causes the gas molecules to move slowly, so they don’t collide as much in quantum circuits..
Dr. Kurt Jacobs, Army Research Laboratory, US Army Combat Capability Development Command. USA
While scientists have made numerous attempts to overcome this problem, a concrete solution has yet to be identified. For now, photonic circuits that integrate nonlinear optical crystals have become the only viable option for quantum computing with solid-state systems at room temperature.
Photonic circuits are a bit like electrical circuits, except that they manipulate light rather than electrical signals. by For example, we can make channels out of a transparent material that photons will travel through, a bit like electrical signals traveling along cables..
Dirk Englund, professor, Massachusetts Institute of Technology
Quantum systems that use photons can avoid limiting cold temperatures, unlike quantum systems that use atoms or ions to preserve data. But to carry out logical operations, photons still need to communicate with other photons. At this time, non-linear optical crystals come into play.
Scientists can design cavities in crystals that momentarily retain photons inside them. Using this technique, the quantum system can determine two different potential states that a qubit can maintain, that is, a cavity without a photon (off) and a cavity with a photon (on). Such qubits can later form gates of quantum logic that eventually produce the framework for unusual states.
This means that scientists can use the unknown state of whether or not a photon is present within a crystal cavity to denote a qubit. Quantum logic gates operate on a pair of qubits simultaneously, and can produce a “quantum entanglement” between these qubits. A tangle like this occurs automatically on a quantum computer, and is necessary for quantum methods to detect applications.
But the researchers applied the concept to develop quantum logic gates using predominantly speculative nonlinear optical crystals, up to this stage. Although it has shown great potential, questions remain as to whether this technique could even result in feasible logic gates.
The use of nonlinear optical crystals had remained a mystery until the MIT research team and the Army laboratory presented a method for achieving a quantum logic gate with this technique, using parts of well-known photonic circuits.
“The problem was that if you have a photon traveling on a channel, the photon has a ‘wave pack’ with a certain shapeJacobs added.For a quantum gate, you need the photon wave packets to stay the same after the gate operation.“
Jacobs continued: “Since the nonlinearities distort the wave packets, the question was if you could load the wave packet into the cavities, make them interact through a non-linearity and then emit the photons again so that they have the same wave packets that they started with. “
As soon as the quantum logic gate was developed, scientists performed several computer simulations of the gate’s operation to demonstrate that it could, in theory, work properly. The actual fabrication of a quantum logic gate with this technique will initially require considerable improvements in the quality of specific photonic components, the scientists said.
“Based on the progress made in the last decade, we expect it to take around ten years for the necessary improvements to be made. However, the process of loading and mitigating a wave packet without distortion is something we should be able to do with current experimental technology, so this is an experiment we’ll work on next.Heuck concluded.
The researchers’ findings were published in a peer-reviewed journal, Physical Review Letters, in April 20thth2020.
Magazine reference:
Heuck, M. et al. (2020) Phase controlled gate using dynamically coupled cavities and optical nonlinearities. Physical Review Letters. doi.org/10.1103/PhysRevLett.124.160501.
