Quantum mechanics sets a limit for the precision of continuous measurement of the position of an oscillator. We show how it is possible to measure an oscillator without quantum back-action of the measurement by constructing one effective oscillator from two physical oscillators. We realize such a quantum mechanics-free subsystem using two micromechanical oscillators, and show the measurements of two collective quadratures while evading the quantum back-action by 8 decibels on both of them, obtaining a total noise within a factor of 2 of the full quantum limit. This facilitates the detection of weak forces and the generation and measurement of nonclassical motional states of the oscillators. Moreover, we directly verify the quantum entanglement of the two oscillators by measuring the Duan quantity 1.4 decibels below the separability bound.
Emergent Quantum Mechanics (Em.QM) is defined here as the attempt to bridge the gap between quantum and classical mechanics, and to restore causality to the atomic world. An example described in the paper shows how a conspiracy of the classical laws produces a replica of the quantum harmonic oscillator. This is achieved using a droplet model of electrons, obeying Newton/Einstein dynamics in combination with Maxwell’s electromagnetic laws. A concise sketch of the droplet theory precedes the sections on the harmonic oscillator. This summary also briefly mentions other successes of the droplet theory, such as the derivation of the fundamental quantum laws
p=λh and
E=h.ν with a practically correct numerical value of Planck’s constant h. Although these subjects were already addressed in earlier publications about Em.QM, recently simpler and more transparent derivations were found and are reported here. Finally, the achievements of Em.QM until now are reviewed. Em.QM does not compete with conventional QM: the latter will always be superior for performing actual calculations, whereas Em.QM is concerned with possible interpretations of quantum phenomena. An assessment is given of the present status of Em.QM in this perspective.
Emergent Quantum Mechanics (Em.QM) is defined here as the attempt to bridge the gap between quantum and classical mechanics, and to restore causality to the atomic world. An example described in the paper shows how a conspiracy of the classical laws produces a replica of the quantum harmonic oscillator. This is achieved using a droplet model of electrons, obeying Newton/Einstein dynamics in combination with Maxwell’s electromagnetic laws. A concise sketch of the droplet theory precedes the sections on the harmonic oscillator. This summary also briefly mentions other successes of the droplet theory, such as the derivation of the fundamental quantum laws
p=λh and
E=h.ν with a practically correct numerical value of Planck’s constant h. Although these subjects were already addressed in earlier publications about Em.QM, recently simpler and more transparent derivations were found and are reported here. Finally, the achievements of Em.QM until now are reviewed. Em.QM does not compete with conventional QM: the latter will always be superior for performing actual calculations, whereas Em.QM is concerned with possible interpretations of quantum phenomena. An assessment is given of the present status of Em.QM in this perspective.