Macroscopic quantum superposition of current states in a Josephson-junction loop

Wilhelm, Frank K.; Wal, Caspar H. van der; Haar, A.C.J. ter; Schouten, R. N.; Harmans, C.J.P.M.; Mooij, J. E.; Orlando, Terry P.; Lloyd, Seth

doi:10.1070/1063-7869/44/10s/s26

Cited by 4 publications

(3 citation statements)

References 23 publications

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“…Assuming that ᎂ 〉 is measured, then, on resonance, there will be a peak in the switching probability for Φ e < Φ 0 /2 and a corresponding dip for Φ e > Φ 0 /2. An example of these results 11,15 is shown in Fig. 2.…”

Section: Box 1 | the Josephson Junction As A Nonlinear Circuit Elementmentioning

confidence: 99%

Superconducting quantum bits

Clarke

Wilhelm

2008

Nature

1,847

1,741

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Superconducting circuits are macroscopic in size but have generic quantum properties such as quantized energy levels, superposition of states, and entanglement, all of which are more commonly associated with atoms. Superconducting quantum bits (qubits) form the key component of these circuits. Their quantum state is manipulated by using electromagnetic pulses to control the magnetic flux, the electric charge or the phase difference across a Josephson junction (a device with nonlinear inductance and no energy dissipation). As such, superconducting qubits are not only of considerable fundamental interest but also might ultimately form the primitive building blocks of quantum computers.

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Section: Box 1 | the Josephson Junction As A Nonlinear Circuit Elementmentioning

confidence: 99%

Superconducting quantum bits

Clarke

Wilhelm

2008

Nature

1,847

1,741

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“…Schrödinger intended his thought experiment to be a proof of principle against the Copenhagen interpretation, but it is worth asking whether his experiment could ever practically be realized (barring obvious ethical questions). Microscopic versions of his experiment involving small assemblages of particles, known as "Schrödinger kittens," are performed all the time [20,21,136,233,268], and these experiments have even been scaled up beyond microscopic size in recent years [116,232,294,321].…”

Section: B Subjective Density Matrices and Proper Mixturesmentioning

confidence: 99%

The Minimal Modal Interpretation of Quantum Theory

Barandes,

Kagan

2014

Preprint

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We do not attempt to wade into the centuries-old philosophical debate regarding the ultimate meaning of probability in terms of anything more fundamental, as encapsulated wonderfully by Russell in 1929 (quoted in [179]): "Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means." Interestingly, this quotation parallels Feynman's famous quip in 1961 that "I think I can safely say that nobody understands quantum mechanics." [110] For our purposes, we treat probability as a primitive, irreducible concept, just as we treat concepts like ontology and epistemology.

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“…This is because the large number of interacting particles and their interaction with its surroundings prevent the quantum behavior at macro-scale to emerge [11]. Despite this, MQS states have been demonstrated experimentally for some systems such as Josephson junctions [12][13][14][15], Cooper-pair boxes [16], Bose-Einstein condensates (BECs) [17,18], Rydberg atoms [19], trapped ions [20]. On the other hand, quantum mechanical oscillators have attained increasing attention for MQS preparation due to notable experimental progress in the micro-fabrication of high-Q mechanical oscillators [21,22] in the quantum regime [23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Macroscopic nonclassical-state preparation via postselection

et al. 2017

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Macroscopic quantum superposition (MQS) states are fundamental to test the classical-quantum boundary and present suitable candidates for quantum technologies. Although the preparation of such states have already been realized, the existing setups commonly consider external driving and resonant interactions, predominantly by considering Jaynes-Cummings and beam-splitter like interactions, as well as the non-linear radiation pressure interaction in cavity optomechanics. In contrast to previous works on the matter, we propose a feasible probabilistic scheme to generate a macroscopic mechanical qubit, as well as phononic Schrödinger's cat states with no need of any energy exchange with the macroscopic mechanical oscillator. Essentially, we investigate an open dispersive spin-mechanical system in absence of any external driving under non-ideal conditions, such as the detrimental effects due to the oscillator and spin energy losses in a thermal bath at non-zero temperature. In our work, we show that the procedure to generate the mechanical qubit state is solely based on spin post-selection in the weak/moderate coupling regime. Finally, we demonstrate that the mechanical superposition is related to the amplification of the mean values of the mechanical quadratures as they maximize the quantum coherence. To the best of our knowledge, this physical mechanism has remained unexplored so far.

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Macroscopic quantum superposition of current states in a Josephson-junction loop

Cited by 4 publications

References 23 publications

Superconducting quantum bits

Superconducting quantum bits

The Minimal Modal Interpretation of Quantum Theory

Macroscopic nonclassical-state preparation via postselection

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