Observing the "quantum Cheshire cat" effect with noninvasive weak measurement

Abstract

One of the common conceptions of nature, typically derived from the experiences with classical systems, is that attributes of the matter coexist with the substance. In the quantum regime, however, the quantum particle itself and its physical property may be in spatial separation, known as the quantum Cheshire cat effect. While there have been several reports to date on the observation of the quantum Cheshire cat effect, all such experiments are based on first-order interferometry and destructive projection measurement, thus allowing simple interpretation due to measurement-induced disturbance and also subject to trivial interpretation based on classical waves. In this work, we report a genuine experimental observation of the quantum Cheshire cat effect with noninvasive weak quantum measurement as originally proposed. The use of the weak-measurement probe has allowed us to identify the location of the single-photon and that of the disembodied polarization state in a quantum interferometer. We furthermore elucidate the paradox of the quantum Cheshire cat effect as quantum interference of the transition amplitudes for the photon and the polarization state which are directly obtained from the measurement outcomes or the weak values.

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Cited by in corpus (13)

• Experimental demonstration of separating the waveparticle duality of a single photon with the quantum Cheshire cat
• Heisenberg-limited metrology via weak-value amplification without using entangled resources
• Direct Characterization of Quantum Measurements using Weak Values
• Isolating noise and amplifying signal with quantum Cheshire cat
• Dynamical Casimir effects with atoms: from the emission of photon pairs to geometric phases
• Angular Momentum Flows without anything carrying it
• Is the dynamical quantum Cheshire cat detectable?
• Separating a particle's mass from its momentum
• Weak Particle Presence
• No-go result for quantum postselection measurements of rank-m degenerate subspace
• Towards scalable active steering protocols for genuinely entangled state manifolds
• Testing time order and Leggett-Garg inequalities with noninvasive measurements on public quantum computers
• Spin exchange of two spin-1/2 atoms