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Frontiers of Engineering Reports on Leading-Edge Engineering from the 2018 Symposium (2019) / Chapter Skim
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Quantum Computing with Noisy Qubits - Sarah Sheldon
Pages 13-18

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From page 13...
... proposed that to properly simulate quantum systems, one must use a quantum computer, but quantum computing was considered impractical because of the inability to control qubits without errors. Quantum computers are made up of individual qubits that are coupled to noisy environments (stray electromagnetic fields or material defects that can exchange energy with qubits)
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From page 14...
... Similarly, phase flips are detected based on sign changes between the groupings of three qubits. SURFACE CODE Quantum error correction codes include stabilizer codes, whose many variants each have different requirements for numbers of qubits and error thresholds.
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From page 15...
... accomplish a logical phase flip. During computation, the physical qubits are initialized as eigenstates of both X and Z stabilizers, operators like XXXX and ZZZZ that track bit flip parity and phase flip parity, respectively, and are maintained in these states by X and Z parity checks performed by the circuits, as shown in figure 1(b)
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From page 16...
... Then the observables that correspond to the qubit Hamiltonian are measured and the energy for that state is calculated. The classical computer updates the phase parameters according to a minimization algorithm (simultaneous perturbation stochastic approximation for this work; Spall 1992)
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From page 17...
... a fermionic Hamiltonian is mapped to a qubit Hamiltonian, whose operators will be the quantities measured at the end of the loop (far right)
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From page 18...
... :2551–2577. L Takita M, Corcoles AD, Magesan E, Abdo B, Brink M, Cross AW, Chow JM, Gambetta JM.
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Key Terms

  • physical qubits
  • surface code
  • logical qubit
  • error correction
  • bit flip

  • quantum error
  • data qubit
  • ancilla qubits
  • error rates
  • data qubits

  • code architecture
  • variational quantum
  • rotated surface
  • superconducting quantum
  • quantum computers

  • hybrid quantum
  • quantum computer
  • quantum eigensolvers
  • nine physical
  • single qubit

  • phase flip
  • qec code
  • qubit labeled
  • flip parity
  • flip errors

  • stochastic approximation
  • classical computer
  • recent experiments
  • qubits using
  • trial state


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