Quantum Computers

Quantum computing is based on the concept of quantum nature of particles. Instead of just binary digits 0 and 1,  quantum computation works on several possibilities a quantum state can have. The basic unit of information in quantum computers is quantum bits or qubits. Any two or more quantum states can be added together superposed and the result will be another valid quantum state, conversely every quantum state can be represented as a sum of two or more other distinct states.

Quantum computing primarily employs two important concepts of quantum physics, superposition and quantum entanglement. In superposition particles are thought of as existing across all the possible states at the same time.However, once a measurement of a particle is made, and for example its energy or position is known, the superposition is lost and now we have a particle in one known state.

Quantum entanglement means that multiple particles are linked together in a way such that the measurement of one particle's quantum state determines the possible quantum states of the other particles even if they separated by several light years. Changing one particle will induce a change in the other.

A 2-bit register in an ordinary computer can store only one of four binary configurations (00, 01, 10, or 11) at any given time, a 2-qubit register in a quantum computer can store all four numbers simultaneously or combination of any two or more configurations because each qubit represents two values,That is a qubit can store a zero, a one, both zero and one, or an infinite number of values in between and be in multiple states (store multiple values) at the same time! If more qubits are added, the increased capacity is expanded exponentially.

It is extremely difficult to get particles to behave in the proper way for a significant length of time. A major difficulty in quantum computing has been any disturbance in a quantum system say a stray photon or wave of EM radiation causes the quantum state to collapse, a process known as decoherence. A quantum computer must be totally isolated from all external interference during the computation phase. Some success has been achieved with the use of qubits in intense magnetic fields, with the use of ions.

Although a fully functioning quantum computer is a longer-term goal, many fundamental and practical discoveries have been made in the name of quantum computing.

A team of NASA and Google engineers announced the D-Wave computer, running an optimization problem, came up with an answer 100 million times faster than a conventional computer with a single core processor. What a D-Wave machine does in a second would take a conventional computer with a single core 10,000 years to perform a similar task.

IBM made a new superconducting chip demonstrates a technique crucial to the development of quantum computers. Google, NASA, Microsoft, IBM, and the U.S. government are all working on this new technology.

  

Russian Telescope detects an Alien Signal?

Russian Astronomers claimed to have detected a strong signal from space actually 95 light years away from a star named HD164595 in the Hercules constellation. The star Contains a planet within it which is the size of Neptune and appears to have the right conditions for supporting life.

Seti(Search for Extraterrestrial Intelligence Institute) a private organization, searches the skies for alien life. Seth Shostak, the director for the Center for SETI Research, cautions people to curb their enthusiasm. There are many different possible explanations for what caused the detection.

SETI's Allen Telescope Array, based in northern California is looking for another signal by pointing their radio telescopes in that direction to see if it can pick up a repeat transmission. 

Gravitational Lensing

Gravitational lensing is the warping of light around objects in space that have a strong gravitational pull like our sun.Einstein general theory of relativity describes how gravity can distort the path of light, altering its trajectory.

 

Lensing can produce multiple images of a distant source a phenomenon termed strong lensing. The foreground lens is a galaxy and when the background source is a quasar or resolved jet, the strong lensed images are usually point-like multiple images; When the background source is a galaxy or extended jet emission, the strong lensed images can be arcs or rings.

 

Microlensing ,the temporary brightening of a star due to the magnification induced by a foreground object that crosses the line of sight to the observer. Microlensing has also been effective in the detection of exoplanets as well.

 

Weak gravitational lensing holds enormous promise in observational cosmology, as the technique, properly employed, can reveal the distribution of dark matter independently of any assumptions about its nature. Dark matter does have mass so we can use gravitational lensing to map the dark matter in the universe.

 

We can use the effect to peer deeper into the Universe than would otherwise be possible with our conventional telescopes. In fact, the most distant galaxies ever observed, ones seen just a few hundred million years after the Big Bang, were all discovered using gravitational lensing. Astronomers use gravitational microlensing to detect planets around other stars. The foreground star acts as a lens for a background star.

 

 

https://www.scientificamerican.com/article/for-first-time-einsteins-relativity-used-to-weigh-a-star/?WT.mc_id=SA_TW_SPC_NEWS&sf86652721=1




 

Super Critical CO2 For Power generation

Using CO2 to generate power will revolutionize how power is generated, built, and distributed. Using super critical CO2 to run the turbines for electricity generation instead of conventional steam(water). We all know that water boils at 100 degree C ,but the boiling point can be raised by increasing the pressure, a further increase in pressure and temperature leads us to a point at which the latent heat of vapourisation is zero, or there is no boiling. Water directly becomes steam. This is the Critical Pressure and the Critical Temperature. For steam this occurs at 374 deg C and 220.6 bar.

In super critical condition the density of gas and liquid becomes equal .The critical point for carbon dioxide occurs at a pressure of 73.8 bar and a temperature of 31.1°C. These parameters make equipment design and reaction set-up relatively simple. For water this occurs at 374 deg C and 220.6 bar. The great advantage of CO2 over water it reaches SCF state at almost room temperature.

CO2 is not produced in the the SCF process, rather already existing CO2 is used. There is no addition to any greenhouse effect. 

The use of CO2 in power turbines has been an active area of research for a number of years, and now multiple companies are bringing early stage commercial products to market.

https://www.youtube.com/watch?v=-gCTKteN5Y4&t=175s

Holography

Holography is a three dimensional recording of an image using interference pattern and not regular image focused on film also called lensless photography.The term ‘hologram’ can refer to both the encoded material and the resulting image. Holography was invented by Dennis Gabor in 1948 later awarded Nobel prize.

The light used to make a hologram must be coherent, i.e. of a single wavelength or frequency and with all the waves in phase.  Before reaching the object, the beam is split into two parts, one the reference beam is recorded directly on the photographic plate and the other is reflected from the object to be photographed and is then recorded. Since the two parts of the beam arriving at the photographic plate have traveled by different paths they combine to create an interference pattern of the object. 

A hologram exhibits a property called parallax, the image will change its appearance if you look at it from a different angle, just as if you were looking at a real 3D object.

The image can be reconstructed even from a damaged or partially available film because every point of the hologram contains the image of the object.

The images are scalable. They can be made with one wavelength and viewed with another, with the possibility of magnification.

Applications

Bubble chamber holography has been performed at the Enrico Fermi National Laboratory.Three-dimensional tracks in a 15-foot deep bubble chamber were recorded. The creation and annihilation of matter and antimatter can be seen through these holograms.

Biomedical applications of holography is actively pursued in the U.S. and Europe. Holograms are made inside live organs through optical fibers, providing more details than any previous alternate techniques.

Instantaneous growth rate of a live plant can be directly observed through a hologram. Using optical fibers, the rigid body movements can be isolated from the net growth information.

Bi-focal contact lenses are being manufactured. Compact discs players use holograms to handle light. Grocery store scanners use spinning holograms. High resolution spectrometers use holographic gratings. Anti-counterfeiting in credit card is now a common practice.

 

 

 

 

LASERS

The acronym LASER refers to "Light Amplification by Stimulated Emission of Radiation".The two terms that are important here are one Spontaneous emission and the others stimulated absorption, stimulated emission.

When atom in the ground state absorbs a photon then the atom is excited to higher energy level this is called stimulated absorption, the atom has a short duration to remain in the exited state,the lifetimes are typically a few nanoseconds ( 10^-9  s) and it jumps back to the lower energy state releasing a photon in the process is called spontaneous emission.

While in the excited state if the atom absorbs a photon having an energy equivalent to the energy difference between the two states and jumps back to the lower energy state is called stimulated emission.

There are two conditions for producing LASERS 1) Stimulated emission 2) Population Inversion meaning there are more atoms in the excited state than the ground state.

There are several other important conditions that our laser must satisfy.  First of all, the light that it produces must be coherent. That is to say, it must emit photons that are in-phase with one another. Secondly, it should emit monochromatic light, i.e. photons of the same frequency (or wavelength).  Thirdly, it would be desirable if our laser's output were collimated , producing a sharply defined "pencil-like" beam of light  Lastly, it would also be desirable for our laser to be efficient, i.e. the higher the ratio of output energy - to - input energy, the better.

Types of lasers

Solid-state lasers have lasing material distributed in a solid matrix (such as the ruby or neodymium:yttrium-aluminum garnet "Yag" lasers). 

Gas lasers (helium and helium-neon, He Ne, are the most common gas lasers) have a primary output of visible red light. CO2 lasers emit energy in the far-infrared, and are used for cutting hard materials.

Excimer lasers (the name is derived from the terms excited and dimers) use reactive gases, such as chlorine and fluorine, mixed with inert gases such as argon, krypton or xenon. When electrically stimulated, a pseudo molecule (dimer) is produced. When lased, the dimer produces light in the ultraviolet range.

Dye lasers use complex organic dyes, such as rhodamine 6G, in liquid solution or suspension as lasing media. They are tunable over a broad range of wavelenigths.

Semiconductor lasers, sometimes called diode lasers, are not solid-state lasers. These electronic devices are generally very small and use low power. They may be built into larger arrays, such as the writing source in some laser printers or CD players.

LASER APPLICATIONS

Many scientific, military, medical and commercial laser applications have been developed since the invention of the laser in 1958. They extend from Medical, Welding and cutting ,Surveying, Laser nuclear fusion, Communications, laser printing, spectroscopy, laser cooling ..etc.