Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: quantum physics – Page 380

In a new study, scientists have observed long-lived excitons in a topological material, opening intriguing new research directions for optoelectronics and quantum computing.

Excitons are charge-neutral quasiparticles created when light is absorbed by a semiconductor. Consisting of an excited electron coupled to a lower-energy electron vacancy or hole, an exciton is typically short-lived, surviving only until the electron and hole recombine, which limits its usefulness in applications.

“If we want to make progress in quantum computing and create more sustainable electronics, we need longer exciton lifetimes and new ways of transferring information that don’t rely on the charge of electrons,” said Alessandra Lanzara, who led the study. Lanzara is a senior faculty scientist at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and a UC Berkeley physics professor. “Here we’re leveraging topological material properties to make an exciton that is long lived and very robust to disorder.”

Read more | >

We present an algorithm of quantum engineering of large-amplitude $$\ge 5$$ high-fidelity $$\ge 0.99$$ even/odd Schrödinger cat states (SCSs) using a single mode squeezed vacuum (SMSV) state as resource. Set of $$k$$ beam splitters (BSs) with arbitrary transmittance and reflectance coefficients sequentially following each other acts as a hub that redirects a multiphoton state into the measuring modes simultaneously measured by photon number resolving (PNR) detectors. We show that the multiphoton state splitting guarantees significant increase of the success probability of the SCSs generator compared to its implementation in a single PNR detector version and imposes less requirements on ideal PNR detectors.

Read more | >

The experimental realization of a recently proposed technique points to new possibilities for imaging molecules using x rays.

Hanbury Brown and Twiss (HBT) interferometry [1] is a versatile technique widely used in various fields of physics, such as astronomy, quantum optics, and particle physics. By measuring the correlation of photon arrival times on two detectors as a function of the photons’ spatial separation, HBT interferometry enables the determination of the size and spatial distribution of a light source. Recently, a novel x-ray imaging technique based on the HBT method was proposed to image the spatial arrangement of heavy elements in a crystal or molecule by inducing those elements to fluoresce at x-ray wavelengths [2].

Read more | >

For one, classical physics can predict, with simple mathematics, how an object will move and where it will be at any given point in time and space. How objects interact with each other and their environments follow laws we first encounter in high school science textbooks.

What happens in minuscule realms isn’t so easily explained. At the level of atoms and their parts, measuring position and momentum simultaneously yields only probability. Knowing a particle’s exact state is a zero-sum game in which classical notions of determinism don’t apply: the more certain we are about its momentum, the less certain we are about where it will be.

We’re not exactly sure what it will be, either. That particle could be both an electron and a wave of energy, existing in multiple states at once. When we observe it, we force a quantum choice, and the particle collapses from its state of superposition into one of its possible forms.

Read more | >

If you know the atoms that compose a particular molecule or solid material, the interactions between those atoms can be determined computationally, by solving quantum mechanical equations—at least, if the molecule is small and simple. However, solving these equations, critical for fields from materials engineering to drug design, requires a prohibitively long computational time for complex molecules and materials.

Now, researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory and the University of Chicago’s Pritzker School of Molecular Engineering (PME) and Department of Chemistry have explored the possibility of solving these electronic structures using a quantum .

The research, which uses a combination of new computational approaches, was published online in the Journal of Chemical Theory and Computation. It was supported by Q-NEXT, a DOE National Quantum Information Science Research Center led by Argonne, and by the Midwest Integrated Center for Computational Materials (MICCoM).

Read more | >

A project led by a group of researchers from Israel’s Bar-Ilan University, in collaboration with TII—the Quantum Research Center in Abu Dhabi, United Arab Emirates, is advancing quantum computing by improving the performance of superconducting qubits, the basic computation units of a superconducting quantum processor. The improved qubit, called a tunable superconducting flux qubit, is a micron-sized superconducting loop where electrical current can flow clockwise or counterclockwise, or in a quantum superposition of both directions.

These quantum features would allow the computer to be much faster and more powerful than a normal computer. For the speed potential to be realized, the quantum computer needs to operate several hundred of qubits simultaneously without having them unintentionally interfering with each other.

As an alternative technology to that existing today in quantum processors, superconducting qubits provide several important advantages: First, they are very fast and reliable; and second, it may be simpler to integrate many flux qubits into a processor compared to current available technology.

Read more | >

In the realm of computing, information is usually perceived as being represented by a binary system of ones and zeros. However, in our everyday lives, we use a decimal system consisting of ten digits to represent numbers. For instance, the number 9 in binary is represented as 1,001, requiring four digits instead of just one in the decimal system.

Today’s quantum computers have emerged from the binary system, but the physical systems that encode their quantum bits (qubits) have the capability to encode quantum digits (qudits) as well. This was recently demonstrated by a team headed by Martin Ringbauer at the University of Innsbruck’s Department of Experimental Physics. According to experimental physicist Pavel Hrmo at ETH Zurich: “The challenge for qudit-based quantum computers has been to efficiently create entanglement between the high-dimensional information carriers.”

In a study published on April 19, 2023, in the journal Nature Communications.

Read more | >