Molecular Spintronics

Molecular Spintronics – A New Technology For Quantum Computing

By Avraham David Sherwood
The Editor in Chief

Organic molecules have developed an innovative and interesting possibility of developing an efficient and stable quantum computer. On the one hand, carbon molecules are more stable and allow for the calculation of a larger amount of cubes and on the other hand, the finer control of molecules is still in its infancy.

IBM 16 Qubit Processor. IBM Research; CC BY-SA

The 2nd quantum revolution is underway. In the next decade, quantum-based computers will revolutionize a variety of fields. General quantum computers (Having efficient and adaptable computing capabilities for programming) will be able to solve complex problems that no classical computer can calculate in a reasonable time. Transistor-based computers (home class computers) encode the information using the binary method. Each piece of information is represented by a bit (binary) and translated into a unique chain consisting of digits 1 and 0. The digital information that goes through the classic computers that we all know today is actually a current flowing into the transistors that make up the processor, with the current passing through the transistor we represent in digit 1 and when there is no current it will be represented in digit 0.

In 1997, theorist Daniel Loss and David DiVincenzo first introduced the basic conditions for the creation of a quantum computer. Compared to standard classical computers, the most basic information on a quantum computer is called a cubit and is actually a single particle. This particle has a quantum feature called spin and, in simple words, it describes the direction in which the particle revolves around itself, just as the Earth rotates around itself relative to a defined axis. The digital value of each particle is translated with respect to which axis the particle rotates. For example, if the axis is oriented toward the north pole of the particle, it represents the spin value in digit 1 and relative to the south pole it represents in numeral 0. If the particle is maintained under the right conditions, it can rotate around the two axes simultaneously, taking advantage of the possibilities space at the same time. When the particle is isolated from the environment it can be found in any axis across the sphere and if it is not fully present towards one of the poles we will call it a so-called superposition, that is, the particle spins a bit around the South Pole and a bit around the North Pole and will therefore be represented by a certain percentage in the book. 0 and another percentage that complements it in figure 1. When hundreds of particles are placed in this super-position, intertwined with each other, that is, the spin values ​​of the particles are related to each other, a piece of information is created that can be effectively found in all the possibilities. This new and strange feature is capable of generating a fast and efficient parallel computing power from the power that we all know on the regular classic computers.

Apart from the spinous base that DiVincenzo offered, he drew attention to the scientific and technological community regarding four more essential conditions for the existence of quantum computers, such as: the life of the stored information, the sensitivity of the system to manipulation, and the quality of reading the information from the complex physical systems. The DiVincenzo model is the leading model today and there are a number of applications that utilize the electron spin feature in favor of computational capabilities through ion traps, superconductors and hole utilization in the diamond crystal structure. The physical conditions needed for such systems are extremely extreme, so they need to be near perfect vacuum, temperatures near absolute zero and isolation from the environment. In addition to these challenging conditions, these systems are very difficult to control as the number of spins (qubits) increases.

Exploratory organic spintronic devices built during the ERC SC2 Synergy Grant; Deepak Venkateshvaran

Molecular Spintronics

Electronics based on the electron’s spin rather than its electrical charge are called spintronics. The size of the spin can be measured and controlled using external magnetic fields. The main use of Spintronics is mainly found in hard memories on home computers and on-disk. Recently, scientists and researchers have discovered that spintronics can be used with chains of carbon molecules and may in the future be used as a basis for gaining quantum computing capabilities. The carbon molecules can be relatively easily coupled at small intervals and even lower the noise level compared to other conductive materials that may be used as cubes. Thanks to noise reduction, carbon molecules can be used for longer, more stable and reliable calculations. In addition to these impressive promises, there are a number of other open-ended problems that remain unsolved, such as the mechanism that extends the quantum stability of organic-molecule-based systems such as carbon, or how to construct electrical circuits for calculation purposes. Even if they manage to overcome these intestinal problems, they will still need to know how to measure the spin of a single molecule and influence it accurately without affecting its environment. In addition to the noise resulting from spin interaction, the electrical noise resulting from weak current is added due to electron jumping between the carbon molecules.

In conclusion, there is still much work to be done in this area, but due to the considerable scientific and technological advances the sphere of spin molecules is gaining momentum and is expanding to a great extent, so this is a great welcome as it opens up new possibilities for quantum technologies.


The article is based on the article Molecular spintronics: new technology offers hope for quantum computing by physicist Deepak Venkateshvaran.
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