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Implementing and characterizing precise multi-qubit measurements
Quantum Physics · Submitted 2 Jun 2016
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim We measure all of these quantities and report high fidelities, indicating that we are measuring the desired quantities precisely and that the measurements are highly non-demolition.
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The abstract, sentence by sentence
There are two general requirements to harness the computational power of quantum mechanics: the ability to manipulate the evolution of an isolated system and the ability to faithfully extract information from it. Quantum error correction and simulation often make a more exacting demand: the ability to perform non-destructive measurements of specific correlations within that system. We realize such measurements by employing a protocol adapted from [S. Nigg and S. M. Girvin, Phys. Rev. Lett. 110, 243604 (2013)], enabling real-time selection of arbitrary register-wide Pauli operators. Our implementation consists of a simple circuit quantum electrodynamics (cQED) module of four highly-coherent 3D transmon qubits, collectively coupled to a high-Q superconducting microwave cavity. As a demonstration, we enact all seven nontrivial subset-parity measurements on our three-qubit register. For each we fully characterize the realized measurement by analyzing the detector (observable operators) via quantum detector tomography and by analyzing the quantum back-action via conditioned process tomography. No single quantity completely encapsulates the performance of a measurement, and standard figures of merit have not yet emerged. Accordingly, we consider several new fidelity measures for both the detector and the complete measurement process. We measure all of these quantities and report high fidelities, indicating that we are measuring the desired quantities precisely and that the measurements are highly non-demolition. We further show that both results are improved significantly by an additional error-heralding measurement. The analyses presented here form a useful basis for the future characterization and validation of quantum measurements, anticipating the demands of emerging quantum technologies.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | There are two general requirements to harness the computational power of quantum mechanics: the ability to manipulate the evolution of an isolated system and the ability to faithfully extract information from it. | background 1.00 | 0.05 | 0.02 | asserted 1.00 |
| s1 | Quantum error correction and simulation often make a more exacting demand: the ability to perform non-destructive measurements of specific correlations within that system. | background 0.96 | 0.05 | 0.03 | asserted 0.95 |
| s2 | We realize such measurements by employing a protocol adapted from [S. Nigg and S. M. | method 0.81 | 0.81 | 0.03 | asserted 0.98 |
| s3 | Girvin, Phys. Rev. Lett. 110, 243604 (2013)], enabling real-time selection of arbitrary register-wide Pauli operators. | method 0.82 | 0.36 | 0.05 | asserted 0.98 |
| s4 | Our implementation consists of a simple circuit quantum electrodynamics (cQED) module of four highly-coherent 3D transmon qubits, collectively coupled to a high-Q superconducting microwave cavity. | method 0.95 | 0.78 | 0.04 | asserted 1.00 |
| s5 | As a demonstration, we enact all seven nontrivial subset-parity measurements on our three-qubit register. | contribution 0.64 | 0.97 | 0.05 | asserted 1.00 |
| s6 | For each we fully characterize the realized measurement by analyzing the detector (observable operators) via quantum detector tomography and by analyzing the quantum back-action via conditioned process tomography. | method 0.97 | 0.96 | 0.05 | asserted 0.98 |
| s7 | No single quantity completely encapsulates the performance of a measurement, and standard figures of merit have not yet emerged. | gap 0.88 | 0.13 | 0.03 | asserted 1.00 |
| s8 | Accordingly, we consider several new fidelity measures for both the detector and the complete measurement process. | contribution 0.87 | 0.86 | 0.05 | asserted 0.91 |
| s9 | We measure all of these quantities and report high fidelities, indicating that we are measuring the desired quantities precisely and that the measurements are highly non-demolition. | result 0.57 | 0.97 | 0.60 | asserted 0.52 |
| s10 | We further show that both results are improved significantly by an additional error-heralding measurement. | result 0.98 | 0.96 | 0.12 | asserted 1.00 |
| s11 | The analyses presented here form a useful basis for the future characterization and validation of quantum measurements, anticipating the demands of emerging quantum technologies. | future work 0.81 | 0.34 | 0.18 | asserted 0.67 |
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The paper
Original abstract
There are two general requirements to harness the computational power of quantum mechanics: the ability to manipulate the evolution of an isolated system and the ability to faithfully extract information from it. Quantum error correction and simulation often make a more exacting demand: the ability to perform non-destructive measurements of specific correlations within that system. We realize such measurements by employing a protocol adapted from [S. Nigg and S. M. Girvin, Phys. Rev. Lett. 110, 243604 (2013)], enabling real-time selection of arbitrary register-wide Pauli operators. Our implementation consists of a simple circuit quantum electrodynamics (cQED) module of four highly-coherent 3D transmon qubits, collectively coupled to a high-Q superconducting microwave cavity. As a demonstration, we enact all seven nontrivial subset-parity measurements on our three-qubit register. For each we fully characterize the realized measurement by analyzing the detector (observable operators) via quantum detector tomography and by analyzing the quantum back-action via conditioned process tomography. No single quantity completely encapsulates the performance of a measurement, and standard figures of merit have not yet emerged. Accordingly, we consider several new fidelity measures for both the detector and the complete measurement process. We measure all of these quantities and report high fidelities, indicating that we are measuring the desired quantities precisely and that the measurements are highly non-demolition. We further show that both results are improved significantly by an additional error-heralding measurement. The analyses presented here form a useful basis for the future characterization and validation of quantum measurements, anticipating the demands of emerging quantum technologies.
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How the literature uses it
1 arXiv paper cite this in 2 sentences
Papers citing it · 1 sentence without a confident label
Cites it as background 1 paper
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The construction of CPTP maps can be further extended if the intermediate measurement outcomes are part of the output together with the state of the quantum system, which leads to an interesting class of quantum channel called a quantum instrument (QI) [ref] .
Quantum Channel Construction with Circuit Quantum Electrodynamics · Quantum Instrument and POVM · 0.81
What it cites · 10 sentences without a confident label
Uses the method or tool of 2 papers
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For this, we perform a third experiment to characterize the measurement process and extract pertinent figures of merit based on the quantum instrument formalism [ref] .
1106.1445 · MEASUREMENT CHARACTERIZATION · 0.93
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This convex optimization was performing using the CVXPY library [ref] .
CVXPY: A Python-Embedded Modeling Language for Convex Optimization · State and process tomography · 1.00
Cites as background 4 papers
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Building on impressive progress in control [ref] , measurement [ref] , and coherence [ref] , experimental quantum information science is addressing increasingly complex challenges, such as quantum error correction (QEC) [ref] and quantum simulation [ref] .
Repeated quantum error correction on a continuously encoded qubit by real-time feedback · INTRODUCTION · 0.97
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Building on impressive progress in control [ref] , measurement [ref] , and coherence [ref] , experimental quantum information science is addressing increasingly complex challenges, such as quantum error correction (QEC) [ref] and quantum simulation [ref] .
Demonstrating Quantum Error Correction that Extends the Lifetime of Quantum Information · INTRODUCTION · 0.97
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Building on impressive progress in control [ref] , measurement [ref] , and coherence [ref] , experimental quantum information science is addressing increasingly complex challenges, such as quantum error correction (QEC) [ref] and quantum simulation [ref] .
High-Fidelity Universal Gate Set for $^9$Be$^+$ Ion Qubits · INTRODUCTION · 0.97
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