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Quantum Computing Hardware

A qubit is in the state (√3/2)|0⟩ + (1/2)|1⟩. What is the probability of getting 1 when it is measured?

  1. A25%
  2. B50%
  3. C75%
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Answer: A. 25%

The probability of getting 1 is the squared magnitude of the amplitude of |1⟩: (1/2)² = 1/4 = 25%. The probability of getting 0 is (√3/2)² = 3/4 = 75%, and the two add up to 100%. Taking the amplitude 1/2 itself as the probability leads to the wrong answer of 50%.

  • A. Correct. (1/2)² = 0.25.
  • B. This takes the amplitude 1/2 itself as the probability. The probability is the squared magnitude of the amplitude.
  • C. This is the probability of getting 0, (√3/2)² = 0.75.
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More Quantum Computing Hardware questions

  1. When the state of a single qubit is represented on the Bloch sphere, what state does a point on the equator represent?
  2. How many probability amplitudes (complex numbers) are needed to describe a general state of a system of 10 qubits?
  3. The state vector (all the probability amplitudes) of 50 qubits is stored in the memory of a classical computer as double-precision complex numbers of 16 bytes each. Which is closest to the memory required?
  4. Two qubits are in the entangled state (|00⟩ + |11⟩)/√2. Which statement is correct?
  5. Which correctly describes what a single-qubit X gate does?