Introduction to QM

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• Introduction

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Introduction to QM

• QM deals with the behaviour of matter and light
  at the atomic and subatomic level.

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Introduction

• Certain phenomena cant be described using
  classical mechanics.

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Introduction

• Certain phenomena cant be described using
  classical mechanics. Such as the behaviour of
  light.

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Introduction

• Certain phenomena cant be described using
  classical mechanics. Such as the behaviour of
  light.
• The observations of certain experiments
  contradict with what is expected using classical
  Physics.

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Introduction

• On the large scale the behaviour of objects can
  be described by classical Physics.

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Introduction

• On the large scale the behaviour of objects can
  be described by classical Physics.
• However it acts peculiarly as we go to a smaller
  level.

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Introduction

• On the large scale the behaviour of objects can
  be described by classical Physics.
• However it acts peculiarly as we go to a smaller
  level.
• (Intuitively this shouldnt be so????)

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Introduction

• However Quantum Theory governs the behaviour of
  large scale objects such as transistors and
  integrated circuits.

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Background

• Basic Problems

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Background

• One of the clear problems is seen when classical
  electrodynamics is applied the model of the atom.

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Background

• One of the clear problems is seen when classical
  electrodynamics is applied the model of the atom.
• In the model electrons move around the nucleus in
  classical orbits.

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Background

• One of the clear problems is seen when classical
  electrodynamics is applied the model of the atom.
• In the model electrons move around the nucleus in
  classical orbits.
• During the motion it was expected that the
  electrons would emit EM waves continuously.

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Background

• As a result of this emission, the electrons would
  lose energy.

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Background

• As a result of this emission, the electrons would
  lose energy.
• Eventually they would fall into the nucleus.

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Background

• As a result of this emission, the electrons would
  lose energy.
• Eventually they would fall into the nucleus.
• Thus according to classical electrodynamics the
  atom is unstable.

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Background

• From experiment this is not true!!

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What is QM? (In Brief)

• A theory based on probability that agrees with
  all known experiments.

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What is QM? (In Brief)

• A theory based on probability that agrees with
  all known experiments.
• Applied to large scale objects. All objects
  exhibit a quantum effect.

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What is QM? (In Brief)

• A theory based on probability that agrees with
  all known experiments.
• Applied to large scale objects. All objects
  exhibit a quantum effect.
• However at a large scale the probability of
  certain quantum effects is negligible.

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What is QM? (In Brief)

• For example, tunneling is a quantum effect. It is
  needed to explain how transistors work.

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What is QM? (In Brief)

• For example, tunneling is a quantum effect. It is
  needed to explain how transistors work.
• Where a probability is assigned to finding an
  electron outside of a potential barrier.

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What is QM? (In Brief)

• For example, tunneling is a quantum effect. It is
  needed to explain how transistors work.
• Where a probability is assigned to finding an
  electron outside of a potential barrier.
• Consider the act of throwing a ball against a
  wall. From Quantum theory there exists a
  probability of the ball tunneling through the
  wall.

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What is QM? (In Brief)

• From our experiences this should not occur.

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What is QM? (In Brief)

• From our experiences this should not occur.
• And will not occur!!

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What is QM? (In Brief)

• From our experiences this should not occur.
• And will not occur!!
• Reason There is a finite but negligible
  probability.