introduction
DESCRIPTION
Introduction. The Quantum World. The “Schrödinger’s Cat” Experiment (1935). The cat is isolated from the environment. The state of the cat is entangled to the one of a typical quantum system : an atom !. “alive”. “dead”. The Quantum World. AND ?. - PowerPoint PPT PresentationTRANSCRIPT
Introduction
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The Quantum World
The “Schrödinger’s Cat” Experiment (1935)
The cat is isolated from the environment
The state of the cat is entangled to the one of a typical quantum system : an atom !
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The Quantum World
The cat is actually a detector of the atom’s state
• Result “dead” : the atom is disintegrated
• Result “alive” : the atom is excited
“dead”“alive”
AND ?
Entanglement
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AND ?OR !
“dead”“alive”
The Quantum World
Quantum Decoherence : Interaction with the environment leads to a transition into a more classical behavior, in agreement with the common intuition !
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The Quantum World
Measurement Postulate
The state of the measured system, just after a measurement, is the state in which we measure the system.
Before the measurement : the system can be in a superposition of different states. One can only make predictions about measurement results.
After the measurement : Update of the state provided by the measurement …
Measurement Problem ?
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The Wigner’s Friend
Effects of an
observation ?
Amplification of Vital Signs
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Quantum properties of Human Eyes
Wigner representation of the POVM element describing the perception of light
Quantum state retrodicted from the light perception
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Quantum state of the cat (C), the light (D) and the atom (N)
State conditioned on the light perception
Effects of an observation
Quantum decoherence induced by the observation
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Let us imagine a detector of “Schrödinger’s Cat” states of light
Effects of this measurement (projection postulate)
Interests of a non-classical measurement
Quantum coherences are preserved !
“AND”