Simulating Quantum Instruments with Projective Measurements and Quantum Postprocessing
(2025) In Physical Review Letters 135(4). p.40202-40202- Abstract
Quantum instruments describe both the classical outcome and the updated state associated with a quantum measurement. We ask whether these processes can be simulated using only a natural subset of resources, namely projective measurements on the system and quantum processing of the postmeasurement states. We show that the simulability of instruments can be connected to an entanglement classification problem. This leads to a computationally efficient necessary condition for simulation of generic instruments and to a complete characterisation for qubits. We use this to address relevant quantum information tasks, namely (i) the noise tolerance of standard qubit unsharp measurements, (ii) nonprojective advantages in information-disturbance... (More)
Quantum instruments describe both the classical outcome and the updated state associated with a quantum measurement. We ask whether these processes can be simulated using only a natural subset of resources, namely projective measurements on the system and quantum processing of the postmeasurement states. We show that the simulability of instruments can be connected to an entanglement classification problem. This leads to a computationally efficient necessary condition for simulation of generic instruments and to a complete characterisation for qubits. We use this to address relevant quantum information tasks, namely (i) the noise tolerance of standard qubit unsharp measurements, (ii) nonprojective advantages in information-disturbance trade-offs, and (iii) increased sequential Bell inequality violations under projective measurements. Moreover, we consider also d-dimensional Lüders instruments that correspond to weak versions of standard basis measurements and show that for large d these can permit scalable noise advantages over projective implementations.
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- author
- Khandelwal, Shishir LU and Tavakoli, Armin LU
- organization
- publishing date
- 2025-07
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Physical Review Letters
- volume
- 135
- issue
- 4
- pages
- 1 pages
- publisher
- American Physical Society
- external identifiers
-
- scopus:105013416679
- pmid:40794063
- ISSN
- 1079-7114
- DOI
- 10.1103/bhr5-g71p
- language
- English
- LU publication?
- yes
- id
- 69ed28ed-fcd5-4cc1-ab47-108cb524cee2
- date added to LUP
- 2025-11-10 14:27:51
- date last changed
- 2025-11-10 14:28:59
@article{69ed28ed-fcd5-4cc1-ab47-108cb524cee2,
abstract = {{<p>Quantum instruments describe both the classical outcome and the updated state associated with a quantum measurement. We ask whether these processes can be simulated using only a natural subset of resources, namely projective measurements on the system and quantum processing of the postmeasurement states. We show that the simulability of instruments can be connected to an entanglement classification problem. This leads to a computationally efficient necessary condition for simulation of generic instruments and to a complete characterisation for qubits. We use this to address relevant quantum information tasks, namely (i) the noise tolerance of standard qubit unsharp measurements, (ii) nonprojective advantages in information-disturbance trade-offs, and (iii) increased sequential Bell inequality violations under projective measurements. Moreover, we consider also d-dimensional Lüders instruments that correspond to weak versions of standard basis measurements and show that for large d these can permit scalable noise advantages over projective implementations.</p>}},
author = {{Khandelwal, Shishir and Tavakoli, Armin}},
issn = {{1079-7114}},
language = {{eng}},
number = {{4}},
pages = {{40202--40202}},
publisher = {{American Physical Society}},
series = {{Physical Review Letters}},
title = {{Simulating Quantum Instruments with Projective Measurements and Quantum Postprocessing}},
url = {{http://dx.doi.org/10.1103/bhr5-g71p}},
doi = {{10.1103/bhr5-g71p}},
volume = {{135}},
year = {{2025}},
}