Quantum Computers :: quantum physics computer

Missing figuresWith todays technology we are able to squeeze millions of micron wide logic gates and wires onto the open of silicon chips. It is only a matter of time until we move into to a point at which the gates themselves willing be made up of a mere handful of atoms. At this scale, matter obeys the rules of quantum mechanics. If computers are to grow smaller and more powerful in the future, quantum technology must substitute or reinforce what we have today. Quantum computers arent limited by the binary temper of the classical physical world. Instead, they depend upon observing the state of qubits (quantum bits) that may establish a one or a zero, a combination of the two, or that the state of the qubit is somewhere between 1 and 0. This blending of states is known as superposition.Here a light source emits a photon along a path towards a half-silvered mirror. This mirror splits the light, reflecting half vertically toward detector A and transmiting sic half towa rd detector B. A photon, however, is a single quantized computer software of light and cannot be split, so it is detected with equal probability at either A or B. Intuition would say that the photon randomly leaves the mirror in either the vertical or horizontal direction. However, quantum mechanics predicts that the photon very travels both paths simultaneously ... This effect, known as single-particle interference, can be snap off illustrated in a slightly more elaborate experiment, outlined in figure b below1In this experiment, the photon first encounters a half-silvered mirror, then a fully silvered mirror, and finally another half-silvered mirror onward reaching a detector, where each half-silvered mirror introduces the probability of the photon traveling deal one path or the other. Once a photon strikes the mirror along either of the two paths after the first beam splitter, the arrangement is uniform to that in figure a, and so one might hypothesize that the photon will reach either detector A or detector B with equal probability. However, experiment shows that in reality this arrangement causes detector A to register 100% of the time, and never at detector B2This is known as quantum interference and results from the superposition of the possible photon states, or say-so paths. So although only a single photon is emitted, it appears as though an similar photon exists and travels the path not taken, only detectable by the interference it causes with the original photon when their paths come together again.