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Graphene

Researchers demonstrate working of quantum computers with help of graphene

A new material consisting of only one sheet of carbon atoms can give rise to new and unique designs of optical quantum computing devices. Researchers from the University of Vienna and Institute of Photonic Sciences, Barcelona have proved that tailored structures of graphene lead to the interaction of singular photons. The study has been published in the npj Quantum Information.

Photons interact with the environment to a very less degree, which makes it quite suitable for the storage and transmission of quantum information. However this same property makes it very difficult to interpret the information which has been stored in them.

For building a quantum photonic computer, it is essential for a photon to alter the state of second. This is called a quantum logic gate and a quantum computer requires millions of these. This can be achieved with the help of a ‘non-linear material’, in which there is interaction of two photons. But the standard non-linear materials are not efficient to construct a quantum logic gate.

However it has been recently understood that the nonlinear interactions can be highly improved with the help of plasmons. Plasmons make the light bind to the electrons which are located at the surface. Then these electrons facilitate a very strong interaction between the photons. In presence of these positives, a drawback is that the plasmons decay in the standard materials before the actual quantum effects can occur.

Philip Walther, from University of Vienna who led the team of researchers made a proposal to manufacture plasmons in the graphene material. Graphene has been only discovered in 2004 by Andre Geim and Konstantin Novoselov at University of Manchester. Though it was observed way back in 1962, it had not been independently isolated and studied then. For their work, the duo was awarded the Nobel Prize in Physics in 2010.

The unique arrangement of electrons in graphene leads to strong nonlinear interactions, which allows the plasmons to remain for a long duration. In the graphene quantum logic gate, scientists have demonstrated that if singular plasmons in nanoribbon are made from graphene, then it allows for the interaction of electrical fields of two plasmons in different nanoribbons. This makes way for quantum computation if each of the plasmons remain in their ribbons, since many gates can be applied to them.

Irati Alonso Calafell, who is the first author on this paper remarked that strong non linear interaction in graphene does not allow two plasmons to be in the same ribbon.

Shield Cryostat XENON 100

Scientists successfully observe radioactive decay of xenon isotope, the slowest process ever detected

The research team of XENON Collaboration built an instrument which captures the processes that take time longer than the formation of the universe. The researchers have reported that they have noticed the radioactive decay of Xenon-124 which has a half-life of 1.8 * 1022 years. The results have been published in the Nature journal.

In this situation, researchers managed to study a special case known as double electron capture in which two protons present in a xenon atom at the same time absorb two electrons which lead to the formation of two neutrons and they also explained that this is the rarest thing which is multiplied by another which makes it ultra rare. Ethan Brown a co-author of the study and an assistant professor of physics at Rensselaer Polytechnic Institute said that they saw the decay happening and it was the slowest process ever and that their dark matter detector can very quick to measure the rarest thing recorded.

The instrument is invented to identify the interactions of hypothetical dark matter particles which have atoms weighing 1,300kg in Xenon isotope which is packed inside the tank of the device. But in this situation the censors instead of recording the particles it recorded the decaying of the isotope in itself which lead to a rare survey of a different kind. The decaying of the xenon isotope was never noticed by scientists directly even if there was a theory behind this since 1955 and it’s the proof of something they have been examining since decades.

XENON1T detects the signals sent by the electron in atoms by reordering themselves to fit for the two that were arrested in the nucleus. Brown said that a room is created in the shell when the electrons in double capture are removed from the innermost shell around the nucleus and the rest collapses in the ground state and this process was observed by them. XENON1T can also be a cause of finding important things and that the recent study can teach us more about neutrinos which are large but very difficult to detect the particles which scientists are looking for decades now.

Here the researchers noticed two-neutrino double electron capture which is due to the reordering of electrons which means two electrons were discharged by the atomic nucleus. Curt Breneman from RPI said that this is a fantastic discovery which helps in gaining more knowledge on the basic features of the matter. Scientists are currently working on upgrading the equipment for XENONnT in which the active mass detector will be thrice larger than XENON1T. It will have an improved sensitivity as compared to XENON1T.

supersolid representation artist

Scientists discover supersolidity in quantum gases for the first time

Francesca Ferlaino and other researchers from Austrian Academy of Sciences and the University of Innsbruck created a report on Physical Review X on what they observed of the behavior of a supersolid in dipolar quantum gases made of dysprosium and erbium. Atoms are arranged in a crystalline pattern as well as they behave like a superfluid in a supersolid where particles can move even when there is no friction.

Dr. Lauriane Chomaz from the Institute for Experimental Physics at the University of Innsbruck and colleagues said that their work was mainly focused on attaining the supersolidity in helium but now the researchers are emphasizing more on atomic gases with strong dipolar interactions. Many experiments have been conducted and it has been observed and disclosed in one of the recent experiments that atomic gases have some common properties of that of superfluid helium and these features are the basic features required for achieving a basic condition with both spontaneous density modulation and global phase coherence.

Density modulation and global phase coherence are the indicators of supersolidity. The team created the two supersolids with the help of erbium and dysprosium quantum gases. The scientists said that they created different states by performing different experiments which will show the features of supersolidity by adjusting the relational strength among the particles in erbium quantum gases as well as the erbium quantum gases.

Dr. Francesca Ferlaino who is the senior author from the University of Innsbruck and the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences said that the way the erbium works is only for the short period of time and he also adds that their dysprosium realization shows an unmatched balance.

In this experiment, the state of supersolidity can not only live longer but the state of supersolidity can be straightforwardly attained through the process of evaporative cooling which can be started from a thermal sample. The simple principle here is like getting energized over a cup of tea. The principle here is removing the particles which are carrying most of the energies so that the gas slowly cools down and down and slowly achieves the quantum-degenerate stationary state along with the help of the characteristics of the supersolid at the thermal equilibrium.

Thus we can conclude here that the experiment offers a very thrilling hope for more experiments in the future and the theories as well since the state of the supersolid is a bit affected by dissipative dynamics or excitations which leads to the pavement so that it can probe its excitation spectrum and its superfluid behavior.

cms higgs event

Scientists develop technique to trap dark particle inside LHC

For a long time, scientists have declared that we are surrounded by dark matter and dark energy which helps in binding the galaxy together. Yet they have not been able to spot them directly. Liano Wang who researches on finding signals in large particle accelerators at LHC and a physics professor at the University of Chicago says that they are confident that there is a dark world where the energy is powerful than ours.

Researchers from the University of Chicago and the university affiliated Fermilab have reported the findings in Physical Review Letters. They have found a creative way of tracing dark matter. They separate the dark particle which they see frequently interacting with normal matter. Researchers estimate that the particles which aren’t yet discovered are big and have longer life span than the particles which are already discovered. Researchers know that the particles can be easily caught when the LHC creates the collision and the number of collisions is measured.

95% or above of the universe is made of the dark world and scientists know it from the effects it creates. The effects are just like supernatural activities we can see it only when something unnatural happens. For example, we know there is a dark matter when we see all galaxies held together and gravity doing its work.

According to the previous research on the working pattern of the universe, Wang said that the particles which have a longer lifespan are somewhat related to Higgs Boson and they are the doorway to the dark world and the Higgs can decompose into these particles. So the problem here is how to rectify the events from all the other events since its very difficult to find out the particles after a collision because more than a billion collisions take place within a second and the subatoms gets scattered in every possible direction. 

Lin said that if it’s heavier then it would fetch the energy to be produced and so the momentum would be low and it would move slower than the speed of light. Researchers can easily twist their algorithm to separate particles that have a longer life span and decompose slower than the remaining subatomic shrapnel. Scientists search for the time difference of less than a billionth of second and they are optimistic towards the LHC censors that they are responsive enough to complete the job. LHC instruments are being updated so that when the collider attacks take place in 2021 they search for the slowly decaying particles.

wormhole travel envisioned by artist

Wormhole travel could be possible, but would also be really slow

A new study conducted by Daniel Jafferis and Ping Gao of Harvard University and Aron Wall of Stanford University shows that wormholes can actually exist in reality. The term wormhole was coined in 1957. Wormholes are speculative structures which link disparate points in spacetime and are based on a special solution of Einstein field equations that are solved with the help of a Jacobian matrix and determinant. It can be visualised as a double ended tunnel joining separate points in spacetime. Although they agree with the General Theory of Relativity, it is not yet certain that they are present.

The authors of the study say that although they are theoretically true, it is not useful for human beings to travel through them. The time to travel through these wormholes is supposedly more than travelling directly, hence it is not much useful for space travel. These findings will be presented by Daniel Jafferis at the 2019 American Physical Society April Meeting.

Although the inter-galactic travel may not take place soon, the finding that a wormhole can be constructed through which light could travel certainly boosts the development of the theory of quantum gravity. The significance of this finding lies in connection to the black hole information problem and the relation between gravity and quantum mechanics.

The motivation for the new theory came when Jafferis thought about two black holes which were entangled at a quantum level as stated in the ER=EPR correspondence. This signifies that the direct path between black holes is smaller than the wormhole connection, thus the wormhole travel is not the shortest path. Travelling through the wormhole can be considered as equivalent to quantum teleportation with the help of entangled black holes.

The theory was based by Jafferis on a setup which was first devised by Albert Einstein and Rosen back in 1935, that consisted of a connection between black holes. Since the wormhole can be traversed through, it was a special case where information could have been derived from a black hole.

The theory gives an insight into regions which would have been behind a horizon otherwise. The major hurdle till now in formulating wormholes which can be traversed through has been the necessity for negative energy, which was inconsistent with the idea of quantum gravity. However, this problem has been overcome by Jafferis with the help of quantum field theory tools.

Jafferis feels that this revelation will help in learning deep concepts about gravity correspondence and also ways to formulate quantum mechanics.

recently observed pentaquark

CERN data unveils three never seen Pentaquarks

Tomasz Skwarnicki, a professor of physics in the College of Arts and Sciences at Syracuse University in New York has discovered data about a new class of pentaquarks. He confirmed the existence of three never seen pentaquarks.

The finding states that the particle, named Pc(4312)+, decays to a proton and a J/ψ particle (composed of a charm quark and an anticharm quark). This latest observation made by him has a statistical significance of 7.3 sigma, passing the threshold of 5 sigma traditionally required to claim a discovery of a new particle.

Skwarnicki is also a part of a team of researchers, including members of Syracuse’s High-Energy Physics (HEP) Group. The research group is religiously involved in studying fundamental particles and forces in the universe. Most of their work takes place at the CERN laboratory in Geneva, whose LHCb is the biggest and evidently the most powerful particle detector in the world. LHCb stands for Large Hadron Collider beauty.

Within the LHC the protons are heaved and flung together at high energies, only to collide with one another. What lies inside the particles, once cracked open, helps scientists probe and enquire into the mysteries of the fundamental universe.

To have a deep understanding of how particles interact and bind together is Skwarnicki’s specialty. In 2015, he and a PhD student Nathan Jurik and a distinguished Professor Sheldon Stone and Liming Zhang, an associate professor at Tsinghua University in Beijing, made headlines with their role in LHCb’s detection of first two pentaquarks. The first two pentaquarks were Pc(4450)+ and Pc(4380)+.

LHCb’s latest data used up an energy beam that was nearly twice as strong. This method when combined with more refined data-selection criteria, produces a greater range of proton collisions.

The data also revealed a third “companion” to it called pentaquark. He adds that “All three pentaquarks had the same pattern similar to that of a baryon with a meson substructure. Their masses were below appropriate for the baryon-meson thresholds”.

Skwarnicki’s discovery occurred relatively fast, considering that LHCb stopped collecting data almost three months ago.

He is excited about the discovery because it helps explain how the smallest constituents of matter behave and change. His latest discovery proves that pentaquarks are built the same way as protons and neutrons, which are bound together in the nucleus of an atom.

Skwarnicki tells that although the pentaquarks don’t play a significant part in the basic matter that humans are made of, their presence and existence will significantly affect the other matter and their models in different parts of the universe such as the neutron stars.

Attoclock

Physicists clocked the ghostly speed of quantum tunnelling

In quantum physics, there has always been suspense that how some particles travel from one place to another, passing impenetrable barriers, without having enough energy to do so. This question has puzzled the scientists for decades that how a particle can ‘tunnel‘ without energy.

In order to understand this process, scientists have been carrying out various experiments. In one such experiment using hydrogen atoms, it was seen that this ‘tunneling‘ process happens instantaneously. This instant tunneling has been investigated before as well, but now scientists have finally observed this process with the help of an instrument called the attoclock.

Robert Sang from Griffith University in Australia stated, “When we use atomic hydrogen, it is observed that there is no delay in what we can measure.”

The attoclock sets up 1,000 ultra-short pulses of light per second to interact with the hydrogen atom, pulses totaling 30 gigawatts of instantaneous power. This created a condition in which the single electron of the atom could be pushed through a barrier.

Sang said, “There’s a well-defined point where we can start that interaction, and there’s a point where we know where that electron should come out if it’s instantaneous. So anything that varies from that time we know that it’s taken that long to go through the barrier. That’s how we can measure how long it takes. It came out to agree with the theory within experimental uncertainty being consistent with instantaneous tunneling.”

It was one of the most mysterious studies of quantum mechanics that the scientists now have a better handle on. The new knowledge that the attoclock provides could be useful anywhere where quantum tunneling is involved including electron microscope and the transistor in our computers.

Quantum tunneling has also been suggested as a way of harvesting energy from excess radiation and waste heat, so more we understand the process of how it actually works, the better. The new researches can be carried out in order to understand how other kinds of atoms tunnel through the barriers and at what speed.

Now that we have learned this process, we can use this process for other atoms possibly to learn about new physics”, says one of the researchers, Igor Litvinyuk from Griffith University.

Published Researchhttps://www.nature.com/articles/s41586-019-1028-3

Quantum Dots with emission maxima in a 10-nm step are being produced at PlasmaChem in a kg scale

Researchers achieved near-perfect performance in low-cost semiconductors

Nowadays the whole world has become digitalized and for each and everything we have an electronic device. We have a television to entertain ourselves, an iPad to watch movies and work on the go, a mobile to receive calls when we are away from home. These electronic devices have something called as the semiconductor.

A semiconductor is a substance whose electrical conductance falls between metal and insulator. However, the conducting property can be altered by adding impurities into the crystal. Some commonly known semiconductors are silicon, germanium, and arsenide. Since it becomes very difficult to produce, semiconductor becomes very expensive.

Quantum dot is the solution and can be used in place of a semiconductor. Quantum dots are basically very small semiconductors which lie in the nanometre scale. Quantum dots change its properties even with a very small change in shape or size. The quantum dots have been used in electronic instruments like solar panels, camera sensors and medical imaging tools by researchers.

David Hanifi co-author of research on quantum dots said, “These quantum dots can be made in large number in labs in a more simple way as compared to semiconductor”.

When the research started in order to understand whether they could compete with semiconductors, the researchers focused on how efficiently the quantum dots could remit the light that they absorb, and the experiments showed that the performance of quantum dots was better as compared to a semiconductor.

This research work is the result of a collaboration between the labs of Alberto Salleo, professor of materials science and engineering at Stanford, and Paul Alivisatos, the Samsung Distinguished Professor of Nanoscience and Nanotechnology at the University of California, Berkeley, who is a pioneer in quantum dot research and senior author of the paper. However, this research is a part of the collection of projects of the Department of Energy at the Frontier Research Centre.

There are various benefits that quantum dots have. Being highly customizable, one of the biggest benefits of quantum dots is that it changes its shape due to which it can change the wavelength of light that they emit which is one of the biggest advantages in colour based applications like television.

Thus, quantum dots have hit the consumer market in the form of quantum dot TV or the QLED(where Q stands for quantum dots).

Samsung QLED TV

Samsung QLED TV 8K – 75 inches. Credit: Bretwa/ wikimedia

As we all know that everything in this universe comes with its own disadvantages, the disadvantage that the quantum dot has is that because of its smaller size – it takes many particles to come together in order to perform a particular task. In order to form so many quantum dots, the chances of something going wrong becomes highly possible, which indirectly means that the chances of some program to go wrong also becomes possible due to which there are chances of performance getting hampered.

The researchers are finding out measurement techniques in order to evaluate these particles.

The next step in the ongoing research involves even more precise measurements and if the researchers can determine that, these quantum dots could reach an efficiency of 99.9 percent or above.

With the increase in efficiency, we can have wonderful applications like:

  • New glowing dyes to enhance our ability to look at biology at the atomic scale.
  • Luminescent cooling and luminescent solar concentrators, which allow a relatively small set of solar cells to take in energy from a large area of solar radiation and many more things.

People working on these quantum dot materials have thought for more than a decade that dots could be as efficient as single crystal materials,” said Hanifi.

So, Let us hope for this research to go forward and get us many other efficient applications.

Published Researchhttp://science.sciencemag.org/content/363/6432/1199

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

JILA 3D Strontium Atomic Clock

Breakthrough: Researchers developing atomic clocks to replace GPS and Galileo

Recently, scientists in the Emergent Photonics Lab (EPic Lab) at the University of Sussex, have made a discovery of an important element of atomic clock devices which could reduce reliance on satellite mapping in the future using cutting-edge laser beam technology.

Dr. Alessia Pasquazi from the EPic Lab in the School of Mathematical and Physical Sciences at the University of Sussex said, “With a portable atomic clock, an ambulance, for example, will be able to still access their mapping whilst in a tunnel, and a commuter will be able to plan their route whilst on the underground or without mobile phone signal in the countryside. Portable atomic clocks would work on an extremely accurate form of geo-mapping, enabling access to your location and planned route without the need for satellite signal.

Our breakthrough improves the efficiency of the part of the clock responsible for counting by 80%. This takes us one step closer to seeing portable atomic clocks replacing satellite mapping, like GPS, which could happen within 20 years.

This technology will change people’s everyday lives as well as potentially being applicable in driverless cars, drones and the aerospace industry. It’s exciting that this development has happened here at Sussex.”

Their invention will greatly improve the efficiency of the lancet (which in a traditional clock is responsible for counting), by 80%. And in the future, portable atomic clocks will completely replace satellite mapping within 20 years.

GPS working

Components involved when updating the GPS almanach using A-GPS and a GSM network (Source: Wikimedia/ Adlerweb)

Professor Marco Peccianti from the University of Sussex EPic Labs said, “We are moving towards the integration of our device with that of the ultra-compact atomic reference (or pendulum) developed by Professor Matthias Keller’s research group here at the University of Sussex. Working together, we plan to develop a portable atomic clock that could revolutionize the way we count time in the future.

Our development represents a significant step forward in the production of practical atomic clocks,and we’re extremely excited by our plans, which range from partnerships with the UK aerospace industry – which could come to fruition within five years –  through to portable atomic clocks that could be housed in your phone and within driverless cars and drones within 20 years.”

According to researchers, the compact laser-based atomic clock developed by the University of Sussex team could revolutionize the way we count time in the future.

More Infohttps://www.nature.com/articles/s41566-019-0379-5