Missing Piece Discovered in the Puzzle of Optical Quantum Computing – Californianewstimes.com

Along Washington University in St. LouisJune 30, 2021

Jung-Tsung Shen, an associate professor of electrical systems engineering, has developed a deterministic and fidelity 2-bit quantum logic gate that utilizes a new form of light. This new logic gate is orders of magnitude more efficient than current technology. Credit: Jung-Tsung Shen

Until now, efficient 2-bit quantum logic gates have been out of reach.

A study at the McKelby Institute of Technology at Washington University in St. Louis found a missing part of the photon computing puzzle.

Jung-Tsung Shen, an associate professor at the Department of Electrical Systems Engineering, Preston M. Green, has developed a deterministic and fidelity 2-bit quantum logic gate that utilizes a new form of light. This new logic gate is orders of magnitude more efficient than current technology.

In the ideal case, fidelity can be as high as 97%, says Shen.

His study was published in the journal in May 2021 Physical Review A..

The potential of quantum computers is linked to the anomalous properties of superposition (the ability of a quantum system to contain many different properties or states at the same time) and entanglement (two particles that function in a non-classical correlation). I am. Manners despite being physically separated from each other.

When a voltage determines the value of a bit (1 or 0) in a classical computer, researchers often use individual electrons as qubits, which are quantum equivalents. Electrons have several properties that make them suitable for tasks. Electrons are easily manipulated and interact with each other by electric or magnetic fields. Interactions are useful when you need to entangle two bits. In other words, it reveals the wilderness of quantum mechanics.

But the tendency for them to interact is also a problem. Everything from stray magnetic fields to power lines affects electrons, which can make it difficult to truly control them.

However, for the past two decades, some scientists have tried to use photons as qubits instead of electrons. If computers have a real impact, we should consider using light to create a platform, says Shen.

The opposite problem can occur because photons are uncharged. Photons do not interact with the environment like electrons, but they do not. It was also difficult to design and create ad hoc (effective) photon interactions. Or so the traditional way of thinking went.

In less than a decade, scientists working on this issue seemed to have done so by measuring two photons when they exited, without having to get entangled when entering the logic gate. I found that I behaved in. A unique feature of measurement is another wild manifestation of quantum mechanics.

Quantum mechanics isnt difficult, but its full of surprises, Shen said.

The discovery of the measurements was groundbreaking, but not at all. This is because for every 1,000,000 photons, only one pair was intertwined. Researchers have been more successful since then, but Shen says, its still not enough for computers. Computers need to perform millions to billions of operations per second.

With the discovery of a new class of quantum photonic states, photonic dimers intertwined in both space and frequency, Shen was able to construct 2-bit quantum logic gates with such efficiency. His predictions of their existence were experimentally tested in 2013, and since then he has found this new form of use of light.

When a single photon enters a logic gate, nothing special happens it goes in and out. But if you have two photons, It was then that we predicted that they could create a new state, the photonic dimer. We found that this new state was important.

A fidelity 2-bit logic gate designed by Jung-Tsung Shen. Credit: Jung-Tsung Shen

Mathematically, there are many ways to design logic gates for 2-bit operations. These different designs are called equivalents. The specific logic gate designed by Shen and his research group is the control phase gate (or control Z gate). The main function of the control phase gate is to be in the negative state of two photons containing the two photons that come out.

On a classic circuit, there is no minus sign, Shen said. But in quantum computing, the minus sign exists and turns out to be important.

Quantum mechanics is not difficult, but it is full of surprises.

Jung Tsun Sheng

When two independent photons (representing two photon bits) enter the logic gate, the logic gate design allows the two photons to form a photonic dimer, Shen said. .. The new quantum photonic state has proved to be very important because it allows the output state to have the correct sign, which is essential for optical logical operations.

Shen has worked with the University of Michigan to test his design as a solid-state logic gate that can operate under moderate conditions. So far, he says, the results look positive.

Shen says this result is confusing to most people, but apparent as a day known to those in the know.

Its like a puzzle, he said. It can be complicated to do, but once you do it, a glance at it will tell you its right.

Reference: May 21, 2021, Two-photon control phase gate realized by photonic dimer by Zihao Chen, Yao Zhou, Jung-Tsung Shen, Pei-Cheng Ku, Duncan Steel Physical Review A..DOI: 10.1103 / PhysRevA.103.052610

This study is supported by the National Science Foundation and is numbered by ECCS. 1608049 and 1838996. This was also supported by the 2018 NSF Quantum Leap (RAISE) Awards.

The McKelby Institute of Technology at Washington University in St. Louis promotes independent research and education with an emphasis on scientific excellence, innovation, and borderless collaboration. McKelvey Engineering has top-ranked research and graduate programs across departments, especially in biomedical engineering, environmental engineering and computing, and has one of the countrys most selective undergraduate programs. With 140 full-time faculty members, 1,387 undergraduate students, 1,448 graduate students, and 21,000 alumni, we are working to solve some of the biggest challenges in society. Students become leaders and prepare to innovate throughout their careers. To catalyze economic development in the St. Louis region and beyond.

Missing Piece Discovered in the Puzzle of Optical Quantum Computing Source link Missing Piece Discovered in the Puzzle of Optical Quantum Computing

See the rest here:

Missing Piece Discovered in the Puzzle of Optical Quantum Computing - Californianewstimes.com