The role of quantum measurements in physical processes and protocols
arXiv:1707.04241 · doi:10.1088/2058-9565/aa6d3e
Abstract
In this mainly pedagogical article, we discuss under what circumstances measurements play a special role in quantum processes. In particular we discuss the following facts which appear to be a common area of confusion: i) from a fundamental point of view measurements play no special role whatsoever: all dynamics that can be generated by measurements can be generated by unitary processes (for which post-selection is no exception), ii) from a purely physical point of view, measurements are not "outside" of quantum mechanics, iii) the only difference between the abilities of measurement-based protocols and unitary circuits for quantum computing comes from practical (technology dependent) constraints. We emphasize the importance of distinguishing between differences that are i) fundamental but without physical import, ii) fundamental and possess physical import, iii) are not fundamental but have practical import. We also emphasize the importance of separating theoretical and experimental elements of measurement, primarily projection and amplification, which are physically very different. Note that since we are concerned with facts regarding physical processes, this article has little if anything to do with interpretations of quantum mechanics.
References in corpus (24)
- Quantum Computing with Very Noisy Devices
- State preservation by repetitive error detection in a superconducting quantum circuit
- Fault-tolerant quantum computation with high threshold in two dimensions
- Quantum feedback control of a superconducting qubit: Persistent Rabi oscillations
- High threshold universal quantum computation on the surface code
- Universal fault-tolerant quantum computation with only transversal gates and error correction
- All-optical versus electro-optical quantum-limited feedback
- Efficient fault-tolerant quantum computing
- Effective fault-tolerant quantum computation with slow measurements
- Advantages of Coherent Feedback for Cooling Quantum Oscillators
- Fault-tolerant thresholds for quantum error correction with the surface code
- Resolving the vacuum fluctuations of an optomechanical system using an artificial atom
- Coherence-enhanced efficiency of feedback-driven quantum engines
- Coherent versus measurement feedback: Linear systems theory for quantum information
- Coherent controllers for optical-feedback cooling of quantum oscillators
- Fault-Tolerant Topological One-Way Quantum Computation with Probabilistic Two-Qubit Gates
- Quantum Trajectory Thermodynamics with Discrete Feedback Control
- On fault-tolerance with noisy and slow measurements
- Thermodynamics of Quantum-Jump-Conditioned Feedback Control
- Quantum effects improve the energy efficiency of feedback control
- Optimal control for fast and high-fidelity quantum gates in coupled superconducting flux qubits
- Comparing resolved-sideband cooling and measurement-based feedback cooling on an equal footing: analytical results in the regime of ground-state cooling
- The Energy Cost of Controlling Mesoscopic Quantum Systems
- Absolute Dynamical Limit to Cooling Weakly-Coupled Quantum Systems