For instance, manipulating the particle in order to know its position very well-physicists call this "squeezing"-requires making its momentum less certain. Here, " uncertainty" refers to Werner Heisenberg's famous formula, which states that in quantum physics, the product of the measurement uncertainties of the position and velocity (more precisely: the momentum) of a particle can never go below a well-defined minimum. "We can now manipulate the oscillatory states of the ions in such a way that their position and momentum uncertainties are distributed among many periodically arranged states." "At that point, things get exciting," says Flühmann, who is first author of the Nature paper. Using appropriately chosen laser beams, these ions are cooled down to very low temperatures at which their oscillations in the electric fields, inside which the ions slosh back and forth like marbles in a bowl, are described by quantum mechanics as so-called wave functions. student Christa Flühmann and her colleagues work with electrically charged calcium atoms that are trapped by electric fields. Their results have been published in the scientific journal Nature. The research group of Jonathan Home, professor at the Institute for Quantum Electronics at ETH Zurich, has now realised such a qubit encoded in an oscillator. However, several years ago, an alternative proposal suggested storing information not in several redundant qubits, but rather in the many oscillatory states of a single quantum harmonic oscillator. A possible remedy for this is quantum error correction, which means that each qubit is represented redundantly in several copies, such that errors can be detected and eventually corrected without disturbing the fragile quantum state of the qubit itself. Quantum bits, or "qubits," which can take on the logical values zero and one simultaneously, and thus carry out calculations faster, are extremely susceptible to perturbations. Credit: Visualisations: Christa Flühmann / Shutterstockīuilding a quantum computer requires reckoning with errors-in more than one sense. The measurement uncertainty can thus be distributed over many such teeth, which in principle enables precise error detection. In the ETH experiment, calcium ions are made to oscillate in such a way that their wave functions look like the teeth of a comb.
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