Two techniques are described that simplify the experimental requirements for measuring and manipulating quantum information stored in trapped ions. The first is a new technique using electron shelving to measure the populations of the Zeeman sublevels of the ground state, in an ion for which no cycling transition exists from any of these sublevels. The second technique is laser cooling to the vibrational ground state, without the need for a trap operating in the Lamb-Dicke limit. This requires sideband cooling in a sub-recoil regime. We present a thorough analysis of sideband cooling on one or a pair of sidebands simultaneously. 03.67.Lx, 32.80.Pj, 42.50.Lc Laser cooling [1][2][3] and electron shelving detection techniques [4][5][6] were developed in the pursuit of better control of a basic physical system, and high precision experiments. Up to now such experiments have concentrated on atomic transitions that offer good prospects as frequency standards, or that allow sensitive detection of some physical effect. The relatively new subject of quantum information theory [7][8][9] has led to interest in a different experimental approach. Here, an important aim is to realise the preparation, coherent control, and detailed measurement of some sufficiently complex physical system. This allows one to realise simple networks of elementary quantum operations (quantum gates), and to test basic ideas in quantum information theory, such as data compression, quantum error correction, and simple quantum algorithms. The new feature is that such experiments do not require high precision as an end in itself (unlike frequency standards), although high precision is of course very desirable, nor do they require sensitivity to some physical effect. Instead, one's attention is focused purely on the logical properties of the state transformations and measurements that can be carried out.The significance of experiments on trapped ions to quantum information physics was recognised by Cirac and Zoller [10], who proposed the use of a linear ion trap to realise the essential elements of a quantum computer. Although a real ion trap will not permit large-scale quantum computing [11][12][13], such a system should allow experiments on a few tens of qubits, and is one of the most promising for such a purpose. Currently a few groups worldwide are developing experiments to pursue such ideas [13].In this paper we consider the question "what is the simplest method to build and operate a linear ion trap quantum information processor?" One of the available options is to use an ion such as calcium or strontium whose ground state has total spin half. The use of the two Zeeman sublevels of the ground state of each ion naturally suggests itself as a means to store each qubit, but currently this option has not received much attention, partly because the method to measure the final state, the "readout" in computer terminology, is not obvious. We propose in sections 1 and 2 a simple electron shelving technique that will permit such measurements. Our metho...
What drives us to search for creative ideas, and why does it feel good to find one? While previous studies demonstrated the positive influence of motivation on creative abilities, how reward and subjective values play a role in creativity remains unknown. This study proposes to characterize the role of individual preferences (how people value ideas) in creative ideation via behavioral experiments and computational modeling. Using the Free Generation of Associates Task coupled with rating tasks, we demonstrate the involvement of valuation processes during idea generation: Preferred ideas are provided faster. We found that valuation depends on the adequacy and originality of ideas and guides response selection and creativity. Finally, our computational model correctly predicts the speed and quality of human creative responses, as well as interindividual differences in creative abilities. Altogether, this model introduces the mechanistic role of valuation in creativity. It paves the way for a neurocomputational account of creativity mechanisms.
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