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Researchers develop new chip to bridge the gap between quantum and classical computing

The Gap between quantum and classical computing is bridged by this new chip

Quantum computers existing today are limited versions of the futuristic quantum computers that we hope to achieve in the future. However, scientists have created the hardware for the “probabilistic computer” – a device to bridge the gap between the standard PCs of today and the genuine quantum computers. The study appears in the Nature journal. 

This probabilistic computer can solve quantum problems using a special trick. It uses a p-bit which is described by the research team as “poor man’s qubit”. In classical computing, a bit can either take the value 1 or 0, while qubits can take both of these values at the same time as per the laws of quantum computing. Meanwhile, the p-bit can take only 1 or 0 at a time, but the switch between two states occurs very quickly. Using the fluctuations properly, researchers can tackle the problems that are considered quantum computing problems without using a real quantum computer. 

In addition to this, the p-bit can operate at room temperature whereas the qubits need super-cold conditions for their operation. P-bits can be easily adapted to the existing computers. Supriyo Datta, an electrical engineer at Purdue University, in Indiana, said that there are a group of problems solved with the help of qubits that can also be solved by the p-bits. Hence getting the name “poor man’s qubit”. 

The result of the research has been a modified magnetoresistive random access memory(MRAM) device for storing information in the computers of the present day. Magnetic orientations are used to represent 0s or 1s using states of resistance. Eight custom-made MRAM p-bit units were put with a controller chip to create a probabilistic computer – where units are used to take a specific value. 

Scientists were able to solve the integer factorization problems, which are usually considered quantum problems. It can also be solved by classical computers however with lesser efficiency. The probabilistic computer along with p-bits represents a middle ground between two ends. Scientists feel that the fully developed p-bit computers would solve integer factorization problems with lesser energy and time than the computers of the present day. 

Ahmed Zeeshan Pervaiz, Purdue University said that the circuit occupies the same area as that of a transistor but performs the function which would take several thousand transistors to perform. The calculation speed could also be increased by parallel operation of a huge number of p-bits. 

For the practical use of these machines, there is a need for more refining which would not take much time. After that, these can handle certain problems until the final leap in quantum computing occurs. Connecting qubits for practical use is a tough challenge until then p-bits can be used for machine learning and optimization problems. 

Journal Reference: Nature

quantum teleportation qubit

Researchers successfully achieve complex quantum teleportation for the first time

For the first time, researchers from Austria and China have managed to teleport three dimensional quantum states. This teleportation of higher dimensional states might play an important role in quantum computers in the coming days.

Scientists from the University of Vienna and the Austrian Academy of Sciences have demonstrated what was previously thought of as only a theoretical possibility. With the scientists from the University of Science and Technology of China, they were able to teleport complex high-dimensional quantum states. This is reported in the journal Physical Review Letters.

Scientists teleported the quantum state of a qutrit to another distant one. Earlier scientists were able to transport qubits, which have only two-level states. But scientists have now successfully teleported a qutrit which was created from the photon and has three-level states.

Since the 1990s, it was known that multidimensional quantum teleportation can be achieved. Manuel Erhard, Vienna Institute for Quantum Optics said that the first step was to design a technique to implement high-dimensional teleportation along with the technology. To teleport a quantum state, it is encoded in the possible paths which can be taken by the photon. Paths can be correlated to three optical fibers. Interestingly, in quantum physics, one photon might be present in all the fibres at once.

Bell measurement is at the core of quantum teleportation. A multiport beam splitter is used that directs photons with the help of many inputs and outputs thereby connecting the optical fibers. Also, auxiliary photons were used which were sent to the multiple beam splitter for interfering with other photons.

By selecting specific interference patterns, quantum information can be sent to a photon situated far away from input photon, without them interacting. This concept can be extended to as many dimensions as possible.

By achieving this, the research team has demonstrated that a quantum internet can be created in the future by transmitting large amounts of information. Anton Zeilinger, a scientist at Austrian Academy of Sciences and the University of Vienna said that the result will help in the connection of quantum computers having information capacities greater than qubits.

Chinese researchers also find immense potential in the field of multidimensional quantum teleportation. Jian-Wei Pan, University of Science and Technology of China said that their research will be the foundation for a quantum network system that can be built in the future. Pan presented his points at the University of Vienna and the Academy recently.

Quantum physicists in the future will also try to demonstrate the teleportation of the entire quantum state of one photon or atom.

Research Paper: Quantum Teleportation in High Dimensions

qubit

Researchers for the first time report quantum teleportation in qutrit

Scientists have successfully completed teleportation of a qutrit which is a piece of quantum information based on three states and this has opened a whole new host of opportunities and possibilities for quantum computing and communication sector.

Until now, Qubits were used for quantum transportation for long distances, however, a new proof of concept study has shown that future quantum networks will be able to carry much more data with lesser interference that was being thought. Bits in classical computing can be in two states, either 1 or 0. However, in quantum computing, there is qubit which can be both 0 or 1 at the same time called superposition. Qutrit has a similar relation to a trit, adding superposition to the classical examples, that are represented as 0,1 or 2. A qutrit can be all of these at one single time, which makes a huge leap in terms of computer processing power or the amount of information that can be sent at once. It adds another level of complexity for quantum computing researchers.

Quantum teleportation is simply getting the quantum information from one place to the other through a process called quantum entanglement. It is a case when two quantum particles are interlinked and one reveals the properties of the other, no matter how far apart they might be present. The quantum information can be beamed via photons of light that might be used in the future to create an unhackable internet network which will be protected by fundamental laws of physics.

By splitting the path of a photon into 3 parts close to each other in a careful manner with lasers, beam splitters and barium crystals, researchers were able to create qutrit and generate entanglement.

The system produced a fidelity of 0.75 over a measurement of 12 states which is an accurate result. The setup remained slow and inefficient but has shown that quantum teleportation is possible. Daniel Garisto reports in Scientific American, that another group of scientists have recorded teleportation across 10 states but their work has not yet been accepted by a peer-reviewed journal. They would also upgrade their systems in the future maybe even to the heights of ququarts.

Researchers mentioned that their work provides a complete toolbox for teleporting a particle in an intact manner by combining previous methods of teleportation of two-particle systems and multiple degrees of freedom. The scientists expect their results will pave way for quantum technology applications in higher dimensions since teleportation plays a central role in quantum networks and repeaters.

Journal Reference: arxiv

Qubits in quantum computing

Scientists find gravity as key to optimal quantum computation

Scientists have been trying persistently to achieve significant success in the field of Quantum Computing but still, there is a huge scope of improvement if we go by the consensus.

But recently the arduous efforts of all the involved scientists have given them something to cheer at, as there is a claim that gravity a natural phenomenon which has been studied extensively will provide the pathway through which in-depth knowledge of quantum computing can be obtained. The scientific community is hailing these findings because there is a belief that quantum computing will bring a drastic change in the power and scale of computation. The study has been published in Physical Review Letters

The reason behind this linkage between gravity and quantum computing are the geometric rules which are used for finding the shortest distance between two points on a curved surface with respect to gravity in General Relativity. Those same geometric rules can be used for finding the most effective methods to process information in quantum computing.

These points of shortest travel – whether across a spherical planet or inside a quantum computing system – are known as geodesics. A noteworthy point regarding this discovery is that it involves a branch of quantum computing which is conformal field theory. Through this new study, there is a possibility of faster calculations in the above-mentioned branch of quantum computing.

Physicist Pawel Caputa who was involved in this discovery expounds that the process of finding minimal length on complexity geometry is equivalent to solving equations of gravity. So this explanation has made it transparent about how gravity is linked to discovery of quantum computing.

Looking at the other side, there is still a requirement where the reduction of error rates should take place. Along with this, scientists are looking to bring down the interference which hinders the computation process. The reason why quantum computing is thought as the future of computing because it functions on the concept of qubits which is also another form of information. The striking feature of a qubit is its ability to represent several states in contrast to binary digits which have only two states (0 and 1).

Therefore, along with this discovery, recent progress has made quantum computing to be more space efficient and significant improvement in accuracy has taken

All of this promises a bright future for the quantum computing field but the finding has been limited and thus it requires much deeper research which will help in finding its multidisciplinary applications.

Simple Qubits

Scientists reversed time using quantum computer

Have you ever imagined the infused tea flowing back into the tea bag or a volcano from “erupting” in reverse? We cannot imagine about these things because we have learned about the second law of thermodynamics which states that the total entropy of an isolated system can never decrease over time. A group of researcher scientist from Russia teamed up with the scientist from the U.S. and Switzerland in order to challenge this fundamental law of energy.

The study’s lead author Gordey Lesovik who heads the Laboratory of the Physics of Quantum Information Technology at MIPT states that “This research is one of the series which adds up to violating the second law of thermodynamics which is closely associated with the notion of arrow of time that puts in position the one way direction of time from past to future.”

The physicists tried to understand if time could reverse itself for a tiny fraction of a second for a particle. They tried to do this by two methods – first by experimenting the electron in empty interstellar space.

Andrey Lebedev co-author from MIPT and ETH Zurich stated that “If we consider an electron in space and we begin to observe it, we can come to know the position of it. If not the position but at least the area can be decided since the laws of quantum mechanics don’t allow us to understand the exact position of the electron.”

The physicist then adds “The evolution of electron can be explained by Schrödinger’s equation. However, it makes no distinction between the past and the future, the region of space containing the electron will spread out very quickly. The uncertainty of the electron’s position is growing.”

Quantum mechanics travelling wavefunctions

Quantum mechanics travelling wavefunctions (Credit: Maschen/ wikimedia)

Valerii Vinokur, a co-author of the paper, from the Argonne National Laboratory, U.S. adds to the discussion that “Mathematically, it means that under a certain condition of transformation called complex conjugation, the equation will describe a smeared electron localizing back into a small region of space over the same time period. However, this is only possible theoretically and not practically.”

The second method of experimentation was done with the help of quantum computing instead of electrons, made out of two or three basic elements called superconducting qubits. They have four stages of the experiment.

The four stages are as follows:

  • Stage 1: Order
    In the first stage, like the electron was imagined to be localized in space, here, the qubit is initialized in a stage called the zero stage.
  • Stage 2: Degradation
    Similar to the electron being smeared out over an increasingly large region of space, the qubits leave the zero stage and become a complex pattern of zeros and ones.
  • Stage 3: Time Reversal
    In this stage similar to the electron being induced to fluctuation by microwave, here, a special program modifies the state of the quantum computer in such a way that it would then evolve “backward”, from chaos toward order.
  • Stage 4: Regeneration
    Again the evolution program starts from stage 2. Provided that the “kick “ has been launched successfully. The program reverses the state of qubits back into the past.
    It was observed that where two qubits were involved, the success rate was around 85 percent, but where 3 qubits or more than 3 qubits were involved more errors happened and it resulted in only 50 percent of the success rate.

Published Researchhttps://www.nature.com/articles/s41598-019-40765-6