laserpointer

A new method of implementing a "non-crackable" quantum cryptosystem can transmit information at a rate of more than 10 times faster than previous trials. Researchers have developed a new approach that overcomes one of the major problems in the implementation of the quantum cryptography system, which improves the prospect of implementing an available "unbreakable" approach for sending sensitive information hidden in light particles The A description of the indistinguishable photon output from the same output port of the beam splitter. By "sowing a burning laser beam" to another laser beam, researchers from the University of Cambridge and the Toshiba European Research Center have demonstrated that allocating encryption at a speed of two to six orders of magnitude higher than the actual early attempt of the quantum cryptosystem The key is possible.

Encryption is an important part of modern life, so that sensitive information can be safely shared. In traditional encryption technology, the sender and receiver of a particular message determine the password, or the key, so only those who know the key can decrypt the information. But as computers become faster and more powerful, encryption passwords become easier to crack. Quantum cryptography guarantees "unbreakable" security by hiding information into light particles or photons emitted from the most powerful laser pointer. In this cryptographic form, quantum mechanics is used to randomly generate a key. The sender, commonly known as Alice, sends the key by polarizing the different polarized photons. The receiver, commonly referred to as Bob, uses a photon detector to measure the polarization direction of the photon, and then the detector converts the photon into bit information, assuming that Bob uses the correct photon detector in the correct order, Get the key.

The advantage of quantum cryptography is that if an attacker tries to block Alice and Bob's message, the password will change itself due to the characteristics of quantum mechanics. Since the first time in the last century 80's was put forward, the quantum password has brought the possibility of achieving unbreakable security. "In theory, an attacker might have all the power under physical law, but they still can not crack the password." However, when trying to build a usable 2000mw green laser system, the problem of quantum cryptography arises. In reality, this is a back and forth game: the creative attacks on the different components of the system are constantly being developed, and the corresponding countermeasures against the attack are constantly evolving.

The most frequently hacked components are photon detectors, which are usually the most vulnerable components of their most vulnerable attacks due to their high sensitivity and complexity. In response to the attack probe, the researchers developed a new quantum cryptographic protocol called Quantum Key Distribution (MDI-QKD), which is known as Measurement Equipment Unrelated. In this way, Alice and Bob do not have a detector per person, instead of sending their brightest laser pointer photons to a central node called Charlie. Charlie lets photons pass through a beam splitter and measure them. These results can reveal the correlation between these bits, but do not reveal their values, still keep the secret. In this device, even if Charlie tries to cheat, the information will remain safe.

MDI-QKD has been experimentally proven, but its information transmission speed is too slow for practical applications in the real world, mainly due to difficulties in generating indifferent particles from different lasers. In order to make it work, the laser pulses emitted by Charlie's beam splitter need to be relatively long, which limits the transmission rate to hundreds of bits per second (bps) or less. The method developed by the researchers overcomes this problem with a technique called pulsed laser sowing in which one of the green astronomy laser beams injects photons into another laser beam. By reducing the amount of time jitter in the pulse, the laser pulse is more pronounced for Charlie, so that shorter pulses can be used. Pulsed laser sowing can also change the phase of the laser beam at a very high rate. The use of this technique in MDI-QKD devices will result in speeds up to 1Mbps, representing an increase of two to six orders of magnitude higher than previous versions.

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Laser cutting uses a high power density laser beam to irradiate the material to be cut, so that the material is quickly heated to the vaporization temperature and evaporated to form a hole. As the beam moves to the material, the hole is continuously formed with a narrow width (such as 0.1mm) , To complete the cutting of the material. Laser cutting can be divided into four categories: brightest laser pointer vaporization cutting, laser melting cutting, laser oxygen cutting and laser scribing and controlling fracture.

Laser vaporization cutting: the use of high-energy laser beam heating the workpiece, the temperature rose rapidly in a very short period of time to reach the boiling point of the material, the material began to vaporize, the formation of steam. These vapors are ejected at high velocities, forming a cut in the material while the vapors are ejected. The vaporization heat of the material is generally large, so a large amount of power and power density is required for burning laser pointer vaporization cutting. Laser vaporization cutting for thin metal materials and non-metallic materials (such as paper, cloth, wood, plastic and rubber, etc.) cutting.

Laser melting cutting: laser melting to melt the metal material, and then through the nozzle coaxial with the beam blowing non-oxidizing gases (Ar, He, N, etc.), relying on the strong pressure of gas to liquid metal discharge, Forming a cut. Laser melting does not require the metal to fully vaporize, the energy required is only vapor cutting 1 / Laser melting cutting is mainly used for some difficult to oxidize the material or active metal cutting, such as stainless steel, titanium, aluminum and its alloys.

Laser oxygen cutting: The principle of high power laser pointer oxygen cutting is similar to oxyacetylene cutting. It uses laser as a preheating heat source, with oxygen and other reactive gases as cutting gas. On the other hand, the molten oxide and the molten material are blown out from the reaction zone to form a notch in the metal. In this way, the gas is oxidized and the oxidation heat is released. As the oxidation process in the cutting process produces a lot of heat, so the laser oxygen cutting the energy required is only melt cutting 1/2, and cutting speed is much larger than the laser vaporization cutting and melting cutting. Laser oxygen cutting is mainly used for carbon steel, titanium steel and heat-treated steel and other easily oxidized metal materials.

Laser scribing and control of fracture: laser scribing is the use of high energy density laser scanning of the surface of brittle materials, the material heated to evaporate a small tank, and then impose a certain pressure, brittle material will crack along the small slot . Lasers for laser scribing are typically Q-switched lasers and CO2 lasers. The controlled fracture is a steep temperature distribution created by the use of a 1000mw laser pointer scribe, creating localized thermal stresses in the brittle material and breaking the material along the trough.

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