| 1. |
- Miklin, Nikolai, et al.
(författare)
-
Exponentially Decreasing Critical Detection Efficiency for Any Bell Inequality
- 2022
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 129:23
-
Tidskriftsartikel (refereegranskat)abstract
- We address the problem of closing the detection efficiency loophole in Bell experiments, which is crucial for real-world applications. Every Bell inequality has a critical detection efficiency η that must be surpassed to avoid the detection loophole. Here, we propose a general method for reducing the critical detection efficiency of any Bell inequality to arbitrary low values. This is accomplished by entangling two particles in N orthogonal subspaces (e.g., N degrees of freedom) and conducting N Bell tests in parallel. Furthermore, the proposed method is based on the introduction of penalized N-product (PNP) Bell inequalities, for which the so-called simultaneous measurement loophole is closed, and the maximum value for local hidden-variable theories is simply the Nth power of the one of the Bell inequality initially considered. We show that, for the PNP Bell inequalities, the critical detection efficiency decays exponentially with N. The strength of our method is illustrated with a detailed study of the PNP Bell inequalities resulting from the Clauser-Horne-Shimony-Holt inequality.
|
|
| 2. |
- Mironowicz, Piotr, et al.
(författare)
-
Quantum randomness protected against detection loophole attacks
- 2021
-
Ingår i: Quantum Information Processing. - : SPRINGER. - 1570-0755 .- 1573-1332. ; 20:1
-
Tidskriftsartikel (refereegranskat)abstract
- Device and semi-device-independent private quantum randomness generators are crucial for applications requiring private randomness. However, they are vulnerable to detection inefficiency attacks and this limits severely their usage for practical purposes. Here, we present a method for protecting semi-device-independent private quantum randomness generators in prepare-and-measure scenarios against detection inefficiency attacks. The key idea is the introduction of a blocking device that adds failures in the communication between the preparation and measurement devices. We prove that, for any detection efficiency, there is a blocking rate that provides protection against these attacks. We experimentally demonstrate the generation of private randomness using weak coherent states and standard avalanche photo-detectors.
|
|
| 3. |
- Smania, Massimiliano, et al.
(författare)
-
Experimental certification of an informationally complete quantum measurement in a device-independent protocol
- 2020
-
Ingår i: Optica. - 2334-2536. ; 7:2, s. 123-128
-
Tidskriftsartikel (refereegranskat)abstract
- Minimal informationally complete positive operator-valued measures (MIC-POVMs) are special kinds of measurement in quantum theory in which the statistics of their d(2)-outcomes are enough to reconstruct any d-dimensional quantum state. For this reason, MIC-POVMs are referred to as standard measurements for quantum information. Here, we report an experiment with entangled photon pairs that certifies, for what we believe is the first time, a MIC-POVM for qubits following a device-independent protocol (i.e., modeling the state preparation and the measurement devices as black boxes, and using only the statistics of the inputs and outputs). Our certification is achieved under the assumption of freedom of choice, no communication, and fair sampling.
|
|
