Quiz: Quantum Entanglement: Spooky Action at a Distance

Question 1

If two particles are entangled and one is measured to be spin-up, what can be said about the spin of the other particle, assuming they were initially in a singlet state?

Accepted Answer

It must be spin-down

Answer

It must also be spin-up

Answer

It could be either spin-up or spin-down, depending on the measurement basis

Answer

The spin state is indeterminate until measured

Question 2

Which of the following best describes the role of locality in quantum entanglement?

Accepted Answer

No information can be used to transmit signals faster than the speed of light

Answer

Entangled particles influence each other instantaneously, regardless of distance

Answer

Entanglement violates the principle of locality

Answer

Locality is irrelevant in quantum mechanics

Question 3

The EPR paradox was proposed by Einstein, Podolsky, and Rosen to argue that:

Accepted Answer

Quantum mechanics must be incomplete because it allows for faster-than-light influences

Answer

Quantum mechanics is a complete theory

Answer

Entangled particles do not exist

Answer

Classical physics can fully explain quantum phenomena

Question 4

In an experiment with entangled photons, if one photon is measured in the basis |0°>, |90°>, and found to be |0°>, what is the guaranteed measurement result for the other photon if measured in the same basis?

Accepted Answer

|90°>

Answer

|0°>

Answer

It is random

Answer

It depends on the distance between the photons

Question 5

Which principle is NOT violated by quantum entanglement according to our current understanding of physics?

Accepted Answer

The speed of light as a speed limit for information transfer

Answer

The uncertainty principle

Answer

Conservation of energy

Answer

Locality

Question 6

When two particles are entangled, their combined state cannot be described as independent states of each individual particle. This is an example of:

Accepted Answer

Non-locality

Answer

Superposition

Answer

Localization

Answer

Independent state description

Question 7

If an observer measures one of two entangled particles and obtains a random result, what does this imply about the other particle’s state before any measurement?

Accepted Answer

The other particle’s state cannot be known until it is measured

Answer

It is also random

Answer

It is determined and opposite to the measured particle

Answer

The state of the other particle is unaffected by the measurement

Question 8

Which experiment provided strong evidence supporting the reality of quantum entanglement over local hidden variable theories?

Accepted Answer

Bell’s Theorem and subsequent experiments

Answer

The Double-Slit Experiment

Answer

The Compton Effect

Answer

Schrödinger’s cat thought experiment

Question 9

An entangled state of two particles is given by the equation: |Ψ⟩ = (|↑↓⟩ − |↓↑⟩)/√2. If the first particle is measured and found to be in the state |↑⟩, what is the state of the second particle?

Accepted Answer

|↓⟩

Answer

|↑⟩

Answer

|0⟩

Answer

An equal superposition of |↑⟩ and |↓⟩

Question 10

Why is quantum entanglement often referred to as “spooky action at a distance”?

Accepted Answer

Because Einstein used this term to express his discomfort with non-local effects in quantum mechanics

Answer

Because it allows for instantaneous communication between particles

Answer

Because entangled particles can affect each other's states instantaneously, regardless of distance

Answer

Because it defies classical physics principles in an unpredictable manner