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Category: quantum physics

New ground-breaking research from the University of Surrey could change the way scientists understand and describe lasers – establishing a new relationship between classical and quantum physics.

In a comprehensive study published by the journal Progress in Quantum Electronics, a researcher from Surrey, in partnership with a colleague from Karlsruhe Institute of Technology and Fraunhofer IOSB in Germany, calls into question 60 years of orthodoxy surrounding the principles of lasers and the laser spectral linewidth – the foundation for controlling and measuring wavelengths of light.

In the new study, the researchers find that a fundamental principle of lasers, that the amplification of light compensates for the losses of the laser, is only an approximation. The team quantify and explain that a tiny excess loss, which is not balanced by the amplified light but by normal luminescence inside the laser, provides the answer to the spectral linewidth of the laser.

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Portable System Boosts Laser Precision, at Room Temperature

Physicists at MIT have designed a quantum “light squeezer” that reduces quantum noise in an incoming laser beam by 15 percent. It is the first system of its kind to work at room temperature, making it amenable to a compact, portable setup that may be added to high-precision experiments to improve laser measurements where quantum noise is a limiting factor.

The heart of the new squeezer is a marble-sized optical cavity, housed in a vacuum chamber and containing two mirrors, one of which is smaller than the diameter of a human hair. The larger mirror stands stationary while the other is movable, suspended by a spring-like cantilever.

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A new system can significantly lower the production costs costs of mass quantum key distribution (QKD) networks, which will make them available to a wider user audience. This will make it possible to use QDK in the regular fiber-optic cable infrastructure. The paper was published in Scientific Reports.

Many have heard about quantum key distribution (QKD), which is also sometimes referred to as quantum encryption. Today, this is one of the safest ways to encode information that can then be used by major banks, military and governmental organizations. In a QDK system, the information is transmitted by quantum radiation, which is extremely hard for eavesdroppers to intercept.

“As a rule, QKD uses a weak laser light with an average number of photons less than unity,” explains Eduard Samsonov, a research associate at ITMO’s Faculty of Photonics and Optical Information. “This light has fundamental special features, the so-called quantum effects that leave no chance for a third party to infiltrate the channel to read the information without being noticed.”

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To calculate the most stable atomic configuration, as well as estimate its hardness, the team relied on a computational method called density functional theory (DFT). DFT has been successfully used throughout chemistry and solid-state physics to predict the structure and properties of materials. Keeping track of the quantum states of all the electrons in a sample, and their interactions, is usually an intractable task. Instead, DFT uses an approximation that focuses on the final density of electrons in space orbiting the atoms. This simplifies the calculation to make it suitable for computers, while still providing very precise results.

Based on these calculations, the scientists found that the Young’s modulus, a measure of hardness, for pentadiamond is predicted to be almost 1700 GPa – compared with about 1200 GPa for conventional diamond.

“Not only is pentadiamond harder than conventional diamond, its density is much lower, equal to that of graphite,” explains co-author Professor Mina Maruyama.

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Physicists at the Max Planck Institute of Quantum Optics (MPQ) have engineered the lightest optical mirror imaginable. The novel metamaterial is made of a single structured layer that consists only of a few hundred identical atoms. The atoms are arranged in the two dimensional array of an optical lattice formed by interfering laser beams. The research results are the first experimental observations of their kind in an only recently emerging new field of subwavelength quantum optics with ordered atoms. So far, the mirror is the only one of its kind. The results are today published in Nature.

Usually, mirrors utilize highly polished metal surfaces or specially coated optical glasses to improve performance in smaller weights. But physicists at MPQ now demonstrated for the very first time that even a single structured layer of a few hundred atoms could already form an optical , making it the lightest one imaginable. The new mirror is only several tens of nanometers thin, which is a thousand times thinner than the width of a human hair. The reflection, however, is so strong it could even be perceived with the pure human eye.

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Earth, as we know it, is only teeming with life because of the influence of our Sun. Its light and heat provides every square meter of Earth — when it’s in direct sunlight — with a constant ~1500 W of power, enough to keep our planet at a comfortable temperature for liquid water to continuously exist on its surface. Just like the hundreds of billions of stars in our galaxy amidst the trillions of galaxies in the Universe, our Sun shines continuously, varying only slightly over time.

But without quantum physics, the Sun wouldn’t shine at all. Even in the extreme conditions found in the core of a massive star like our Sun, the nuclear reactions that power it could not occur without the bizarre properties that our quantum Universe demands. Thankfully, our Universe is quantum in nature, enabling the Sun and all the other stars to shine as they do. Here’s the science of how it works.

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Admin and Founder of The Secrets of the Universe and former intern at Indian Institute of Astrophysics, Bangalore, I am a science student pursuing Master’s in Physics from India. I love to study and write about Stellar Astrophysics, Relativity & Quantum Mechanics.

Mercury.

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A new spin on the magnetic compression of plasmas could improve materials science, nuclear fusion research, X-ray generation and laboratory astrophysics, research led by the University of Michigan suggests.

The study shows that a spring-shaped magnetic field reduces the amount of plasma that slips out between the .

Known as the fourth state of matter, plasma is a gas so hot that electrons rip free of their atoms. Researchers use magnetic compression to study extreme plasma states in which the density is high enough for quantum mechanical effects to become important. Such states occur naturally inside stars and gas giant planets due to compression from gravity.

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MIT engineers develop a hybrid process that connects photonics with “artificial atoms,” to produce the largest quantum chip of its type.

MIT researchers have developed a process to manufacture and integrate “artificial atoms,” created by atomic-scale defects in microscopically thin slices of diamond, with photonic circuitry, producing the largest quantum chip of its type.

The accomplishment “marks a turning point” in the field of scalable quantum processors, says Dirk Englund, an associate professor in MIT’s Department of Electrical Engineering and Computer Science. Millions of quantum processors will be needed to build quantum computers, and the new research demonstrates a viable way to scale up processor production, he and his colleagues note.

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