Shri Radhe

A great time to explore and enhance devotional and spiritual knowledge in Vrindavan.... Shri Krishna hare Krishna hare Krishna.....

Rainer Weiss: 50 years of LIGO and gravitational waves..Hare Krishna hare Krishna hare Krishna

As one of the key experimentalists to conceptualize and then build one of the biggest experiments in history, Nobel-prize-winning physicist Rainer Weiss’s path to success is remarkable. Now aged 90 he talks to Sidney Perkowitz about his life and work, from the unexpected sources for scientific inspiration to the challenges of large-scale experiments.

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Down-to-earth, unassuming, and keen to discuss his research, physicist Rainer Weiss is remarkably easy to talk to. Five years ago, his work earned him half the 2017 Nobel Prize for Physics, with the other half going to Barry Barish and Kip Thorne, for “decisive contributions to the LIGO detector and the observation of gravitational waves”. The US-based Laser Interferometer Gravitational-Wave Observatory (LIGO) is where gravitational waves were first observed in 2015, definitively confirming the last remaining untested prediction from Albert Einstein’s century-old general theory of relativity.

Despite portending their existence, Einstein himself doubted that these waves would ever be observable because they are extremely weak. Weiss’s breakthrough idea of using laser interferometry finally made possible that first observation – of gravitational waves emitted from the merger of two black holes, 1.3 billion light-years away from Earth – and the many more that LIGO has since detected. It took decades of effort from Weiss, his Nobel colleagues and many others, and the discovery represented a pinnacle in physics that also ushered in a new era in astronomy. Since the advent of observational astronomy, we had been scanning the universe mostly by observing first visible light, then a broad spectrum of electromagnetic waves. Now gravitational waves were able to provide a new way of probing many cosmic phenomena. Only seven years after the birth of gravitational astronomy, it has already produced much valuable new knowledge.

Hare Krishna.Hare Krishna .......

Weiss was born in Berlin, Germany on 29 September 1932, during the Nazis’ rise to power. Weiss’s father, Frederick, who Rainer describes as “an ardent and idealistic communist” from a young age, was a physician. As a Jew and an anti-Nazi communist, who had testified against a Nazi doctor accused of malpractice, Frederick was detained by the Nazis when Rainer’s mother, Gertrude, was pregnant with him. At the behest of his Christian wife, whose family had some local contacts, Frederick was released and sent to Prague. Once Rainer was born, Gertrude travelled with her new baby to join Frederick in Czechoslovakia, where the couple had another child, Sybille, in 1937.

But when the 1938 Munich Agreement allowed German troops to enter Czechoslovakia, the family had to escape once more. “We heard the decision on a radio while on vacation in Slovakia and joined a large group of people heading toward Prague to attempt to get a visa to emigrate to almost anywhere else in the world that would accept Jews,” Rainer recalls in his Nobel biography. The family moved to the US in 1939. Under the immigration law at that time, this was only possible because of Frederick’s profession and because a “very wonderful woman” as Weiss calls her, from the philanthropic Stix family of St Louis, posted a bond to guarantee that the Weisses would not be a burden to the community.

Weiss was raised in New York City, where he initially attended public school. In the fifth grade, he received a scholarship, via a local refugee relief organization to join Columbia Grammar School – a private school in mid-Manhattan, which at one time was associated with preparing students for Columbia University. Music, science and history were his favourite courses, and as a teenager he built custom high-fidelity or “hi-fi” audio systems for classical music lovers.

That interest and his own curiosity eventually brought him to physics. Seeking perfect sound reproduction, Weiss tried to electronically eliminate the background noise a phonograph needle makes as it moves along the groove in an old-fashioned record, which marred the music. But his efforts failed and he decided to go to college to learn enough to enable him to solve the problem. That education began at Massachusetts Institute of Technology (MIT) in 1950..

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Electronics to physics, via a detour

As an electrical engineering major at MIT, Weiss was expected to learn about generators and transmission lines before he could study the electronics that really interested him. This rigid plan was not to his taste, so in his second year he switched to physics, because “it had fewer requirements” and a more flexible curriculum. But that did not immediately work out either. In 1952 Weiss fell in love with a young woman, a pianist. The relationship did not end well and, heartbroken, Weiss failed all of his courses and had to leave MIT.

But all was not lost. By the spring of 1953 he returned to MIT as a technician working in the Atomic Beam Laboratory of physicist Jerrold Zacharias, who had developed the first atomic clock. “The science being done in that laboratory was exquisite,” Weiss recalls. “The experiments there were looking at the properties of isolated single atoms and molecules unperturbed by neighbouring systems. Each atom was the same as the next and it was possible to ask fundamental questions about their structure and the interactions that held them together.” What started off as a role helping grad students with their thesis projects eventually led to Weiss working directly with Zacharias on developing the caesium atomic beam clock, which would eventually go on to be adopted as the standard of time for the Bureau of Standards (now the National Institute of Standards and Technology) and the US Navy..

The escalation of spiritual knowledge through murmurings and chanting the name of Hare Krishna..

For the longest time: Quantum computing engineers set new standard in silicon chip performance. Shri Radhe Shri Radhe...

Two milliseconds—or two thousandths of a second—is an extraordinarily long time in the world of quantum computing. On these timescales the blink of an eye—at one 10th of a second—is like an eternity..

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Now a team of researchers at UNSW Sydney has broken new ground in proving that 'spin qubits'—properties of electrons representing the basic units of information in quantum computers—can hold information for up to two milliseconds. Known as 'coherence time', the duration of time that qubits can be manipulated in increasingly complicated calculations, the achievement is 100 times longer than previous benchmarks in the same quantum processor.

"Longer coherence time means you have more time over which your quantum information is stored—which is exactly what you need when doing quantum operations," says Ph.D. student Ms Amanda Seedhouse, whose work in theoretical quantum computing contributed to the achievement.

"The coherence time is basically telling you how long you can do all of the operations in whatever algorithm or sequence you want to do before you've lost all the information in your qubits."

In quantum computing, the more you can keep spins in motion, the better the chance that the information can be maintained during calculations. When spin qubits stop spinning, the calculation collapses and the values represented by each qubit are lost. The concept of extending coherence was already confirmed experimentally by quantum engineers at UNSW in 2016..

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Hare Krishna hare Krishna.. Krishna Krishna hare...

Indoor high-precision visible light positioning system using non-line-of-sight method.shri Radhe. Shri Radhe.. Hare Krishna...

Location-based services are becoming increasingly important in indoor environments with the development of Internet-of-thing (IoT) technologies. The visible light positioning (VLP) system offers great potential because of its immunity to radio frequency-induced electromagnetic interference, a free and unrestricted spectrum, and a much higher level of security....

The high level of security of the radio frequency....

Recently, a lot of research work on line-of sight (LOS) VLP have been demonstrated with high accuracy at very low costs. However, for LOS VLP, blocking and shadowing is a major problem; and there is the requirement for large numbers of LEDs. Few methods to solve this problem have been investigated.

In a study published in Optics Express, Dr. Lin Bangjiang's group from the Fujian Institute of Research on the Structure of Matter of the Chinese Academy of Sciences proposed a non-line-of sight (NLOS) VLP system using a binocular camera and a single light-emitting diode (LED). It can realize 3D high-precision positioning of an arbitrary posture by the reflected lights from the floor.

The researchers proposed a system model which consists of two function modules: a NLOS optical camera communication (OCC) module and a binocular stereo vision module. The former uses the reflections to receive the coordinate information of the LED by an improved OCC signal recovery model. And the later estimates the camera's position by a proposed binocular position estimation algorithm, which is based on the principles of binocular stereo vision.

They then proposed an error compensation algorithm to optimize the error of the system on the z-axis, which is the key problem about depth estimation for the binocular camera that the error on the z-axis is far greater than that on the x and y axes.

Additionally, the researchers designed an experimental testbed and chose a STM32 microcontroller unit to driver a LED. At the receiver, they used a binocular camera to capture the reflected lights from the ground at two different exposure modes (one long and one short).

They gained the LED position by the NLOS OCC module using the short exposure image, and got the pixel coordinates of the projection of the LED reflected by the ground in the long exposure image. An inertial measurement unit is fixed together with the binocular camera to measure its pose.

Using this information, the researchers calculated the error between the estimation value and the measured value of the camera's position.