Environment and technology
The promises of quantum technologies Based on the unusual behaviour of microscopic quantum objects, new technology aims to bring radical computing capacity and bulletproof encryption.
Secure messaging Quantum encryption has been implemented many times using optical fibres over distances greater than 100 km. In August 2016 China placed equipment into orbit to test satellite-based quantum cryptography.
Journalist: Daniel Saraga Infographics: onlab, Thibaud Tissot
Gravitation Based on the wave nature of atoms, atom interferometers can detect minute changes in the gravitational field, which can be useful as gyroscopes for inertial navigation (e.g., for submarines) or in geological surveys for mineral or oil.
ntum Qua Secure Timekeeping Clocks built on entangled qubits are already more accurate than the usual atomic clocks used in GPS satellites, and better for defining the official duration of a second.
A timeline for new technologies
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Microscopy A new imaging device using entangled photons could improve microscopy in low light.
Magnetic sensor A crystal defect found in diamonds acts as an isolated artificial atom sensitive to extremely weak magnetic fields, useful for medical imaging or oil exploration. This sensor would replace SQID, an existing quantum technology based on superconducting materials but only functional at –170° C.
Quantum sensing The wave nature of quantum matter is extremely delicate and sensitive to its environment. Measuring how fast it decays (the decoherence) allows it to detect and quantify incredibly weak signals. Quantum communication Entangled photons (light particles) can be used for encryption. A sender and a receiver create and instantaneously share a random succession of bits (011011101011 …), which acts as a secret key to encode a message. The latter is sent by conventional means, but only the receiver can decode it, as only she holds the key.
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Quantum computers Information stored as quantum bits (qubits) is very fragile, but quantum entanglement and parallelism in principle allow us to solve certain problems far quicker than with usual computers.
Quantum internet Long distance transmission of qubits could be used to create a secure web. Circumventing signal losses would, however, require quantum repeaters – devices that do not yet exist. Improved single photon sources and detectors would also be needed to increase bandwidth.
A quantum Switzerland
A universal machine A genuine quantum computer would, in addition, solve algebraic problems such as factorising numbers (useful to crack current encryption protocols) and searching databases. It would require thousands or millions of individually addressable qubits.
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Quantum simulators Basic quantum computers will be able to imitate other molecular systems, which is impossible on standard computers. So-called quantum annealers could solve optimisation problems (such as finding the quickest route).
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Harnessing strange properties
With a CHF 115 million budget for 2011 – 2018, the research programme NCCR Quantum Science & Technology involves five universities and IBM Zurich. The University of Geneva and its startup ID Quantique are world leaders in quantum cryptography. The University of Basel has pioneered quantum computers in semiconductors and measurements at the atomic scale. ETH Zurich scientists are an authority on D-Wave, work on various quantum computers and fix loopholes in quantum cryptography.
Wave and particles Very small objects such as electrons, atoms or photons exhibit quantum b ehaviour that can be manipulated – provided they are extremely well isolated from their environment. Quantum information Digital information can be stored in quantum bits or qubits, defined, for example, by the rotational direction of an electron or the energy level of an atom.
First steps The best laboratory machines can control just a dozen qubits. The company D-Wave rents machines with 1,152 qubits, but its claims of quantum speed beyond standard computers have been invalidated.
Superposition One qubit can represent both 0 and 1 at the same time and with arbitrary weight. Parallelism Several qubits can be processed at the same time.
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Entanglement Entangled qubits share an intrinsic link: measuring one will instantaneously affect the other, whatever the distance.
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