* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download powerpoint slides
Ensemble interpretation wikipedia , lookup
Topological quantum field theory wikipedia , lookup
Relativistic quantum mechanics wikipedia , lookup
Renormalization group wikipedia , lookup
Scalar field theory wikipedia , lookup
Basil Hiley wikipedia , lookup
Renormalization wikipedia , lookup
Particle in a box wikipedia , lookup
Path integral formulation wikipedia , lookup
Measurement in quantum mechanics wikipedia , lookup
Quantum decoherence wikipedia , lookup
Probability amplitude wikipedia , lookup
Quantum field theory wikipedia , lookup
Bell test experiments wikipedia , lookup
Hydrogen atom wikipedia , lookup
Copenhagen interpretation wikipedia , lookup
Quantum dot wikipedia , lookup
Density matrix wikipedia , lookup
Double-slit experiment wikipedia , lookup
Coherent states wikipedia , lookup
Wave–particle duality wikipedia , lookup
Bell's theorem wikipedia , lookup
Quantum fiction wikipedia , lookup
Wheeler's delayed choice experiment wikipedia , lookup
Symmetry in quantum mechanics wikipedia , lookup
Orchestrated objective reduction wikipedia , lookup
Many-worlds interpretation wikipedia , lookup
Theoretical and experimental justification for the Schrödinger equation wikipedia , lookup
Quantum electrodynamics wikipedia , lookup
Quantum entanglement wikipedia , lookup
Interpretations of quantum mechanics wikipedia , lookup
Bohr–Einstein debates wikipedia , lookup
EPR paradox wikipedia , lookup
Quantum group wikipedia , lookup
Quantum computing wikipedia , lookup
History of quantum field theory wikipedia , lookup
Quantum machine learning wikipedia , lookup
Canonical quantization wikipedia , lookup
Quantum state wikipedia , lookup
Hidden variable theory wikipedia , lookup
Quantum cognition wikipedia , lookup
Quantum teleportation wikipedia , lookup
Quantum Cryptography and Quantum Computing Cryptography is about a) manipulating information b) transmitting information c) storing information Computing is about a) manipulating information b) transmitting information c) storing information What fundamental concepts of quantum physics were explored in the quantum video? a) b) c) d) measurement-disturbance and many worlds wave-particle duality and the pilot wave many worlds and the pilot wave measurement-disturbance and wave-particle duality Wave-particle duality means that a quantum object can be in two places or states at one time. This is called a superposition and it is essential for quantum computing. Measurement-disturbance is essential for quantum cryptography. Entanglement is used for both cryptography and computing. Quantum Cryptography One method of cryptography uses a long random string of digits - a key - to encrypt and then decrypt a message. The key must be random, as long as the message and it can only be used once. Only quantum physics can provide truly random keys. Quantum physics can also provide a secure way to transmit these keys. It uses entangled polarized photons. To understand polarized photons, you just need to take your understanding of polarized light and imagine what will happen if the light is so faint, there is only one photon. A photon has passed through a vertical polarizer. It heads towards a second one. What are the chances that the photon will be able to pass through it? a) 0% if it is vertical and 100% if it is horizontal b) 100% if it is vertical and 0% if it is horizontal c) 50% if it is vertical and 50% if it is horizontal d) 100% if it is vertical and 100% if it is horizontal A photon has passed through a vertical polarizer. It heads towards a second one. What are the chances that the photon will be able to pass through it? a) 0% if it is +45 and 100% if it is -45 b) 100% if it is +45 and 0% if it is -45 c) 50% if it is +45 and 50% if it is -45 d) 100% if it is +45 and 100% if it is +45 A photon has passed through a vertical polarizer. It then passed through one at +45. What are the chances that the photon will be able to pass a third? a) 0% if it is vertical and 100% if it is horizontal b) 100% if it is vertical and 0% if it is horizontal c) 50% if it is vertical and 50% if it is horizontal d) 100% if it is vertical and 100% if it is horizontal Alice sends Bob a key using polarized photons. Animation of bb84 Eve tries to eavesdrop. • She doesn’t know what basis to use. • Suppose a vertical photon was sent and she chose diagonal polarizers. • The value she got is meaningless and she will send Bob a diagonal photon, not a vertical one. • If Bob uses the correct basis, he might get a horizontal photon instead of vertical and Eve’s presence will be detected. Suppose Eve intercepted 16,000 photons. How many times will she get caught? 1) 8,000 2) 4,000 3) 2,000 4) 1,000 Quantum Computers Computers are based on quantum devices transistors - which are getting smaller and smaller. Soon they will be so small that they will be directly subject to quantum rules. This is both a problem and an opportunity. We will be looking at the opportunity. Quantum computation is fundamentally different from classical computation. Our present computers store information in bits, which can be either a 0 or a 1. A quantum computer stores information in qubits. These can be both a 0 and a 1 because quantum objects can be in a superposition of two states at one time. When the object is measured, it is disturbed, and is always found in one state or the other – 0 or 1. polarization spin energy level The real power comes when you have entangled qubits. Three qubits can be in all the possible bit combinations at once; 000, 001, 010, 011, 100, 101, 110 and 111. That’s eight pieces of data - not three. When measured, you will get one of them. 000 001 010 011 100 101 110 111. How many bits can you store in 20 qubits? a) 1,000 b) 10,000 c) 100,000 d) 1,000,000 What might a quantum computer do that a classical computer can’t? • Simulate quantum systems • Make a really fast search engine • Factor really big numbers* * Which is why we need quantum cryptography! To get a feeling for how quantum computation is fundamentally different from classical computation, we are going to look at quantum tic tac toe. Superposition 1 1 Many games/calculations at a time. 1 1 1 1 Entanglement 2 1 2 1 1 2 2 2 1 1 Measurement-Disturbance 3 2 1 1 1 2 2 3 2 3 1 3 Random Classical States 1 2 1 2 3 3 1 2 4 3 1 2 1 2 4 4 3 3 4 1 2 1 4 5 2 3 1 2 5 4 3 1 2 5 4 5 4 5 4 3 3 1 1 5 4 2 2 6 3 5 1 4 5 4 6 5 6 3 6 2 4 3 Weird Quantum Result 1 1 5 4 2 2 6 3 5 1 6 3 4 5 4 2 6 3 Weirder Quantum Result 6 4 2 8 1 1 3 7 5 6 4 8 1 3 8 3 5 5 7 8 6 4 6 7 2 4 2 http://www.paradigmpuzzles.com/QT3Play.htm 1 3 5 2 7