Nondeterministic noiseless amplification via non-symplectic phase space transformations

Walk, Nathan; Lund, Austin P.; Ralph, T. C.

doi:10.1088/1367-2630/15/7/073014

Cited by 28 publications

(26 citation statements)

References 54 publications

(91 reference statements)

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“…For a loss channel, the effective parameters {χ e , τ e , ε e } have been computed in Refs. [51,52], but can also be found in the Appendix B. Before we apply this technique, let us give a brief description on how NLA works.…”

Section: B Thermal Channelsmentioning

confidence: 99%

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Simulation of Gaussian channels via teleportation and error correction of Gaussian states

2018

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Gaussian channels are the typical way to model the decoherence introduced by the environment in continuous-variable quantum states. It is known that those channels can be simulated by a teleportation protocol using as a resource state either a maximally entangled state passing through the same channel, i.e., the Choi-state, or a state that is entangled at least as much as the Choistate. Since the construction of the Choi-state requires infinite mean energy and entanglement, i.e. it is unphysical, we derive instead every physical state able to simulate a given channel through teleportation with finite resources, and we further find the optimal ones, i.e., the resource states that require the minimum energy and entanglement. We show that the optimal resource states are pure and equally entangled to the Choi-state as measured by the entanglement of formation. We also show that the same amount of entanglement is enough to simulate an equally decohering channel, while even more entanglement can simulate less decohering channels. We, finally, use that fact to generalize a previously known error correction protocol by making it able to correct noise coming not only from pure loss but from thermal loss channels as well.arXiv:1803.03516v2 [quant-ph] 1 Jul 2018

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Section: B Thermal Channelsmentioning

confidence: 99%

“…The effective parameters for a thermal loss channel {χ e , τ e , ε e } have been computed in Refs. [51,52], and are given by…”

Section: Effective Parameters Of the Nlamentioning

confidence: 99%

Simulation of Gaussian channels via teleportation and error correction of Gaussian states

2018

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“…Further discussion of this point can be found in Ref. [15]. More intuitively, we can see the extra noise as being due to our incomplete knowledge of the target state.…”

Section: And the Converse As The Reverse Inference (Ementioning

confidence: 90%

Measurement-based noiseless linear amplification for quantum communication

et al. 2014

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Entanglement distillation is an indispensable ingredient in extended quantum communication networks. Distillation protocols are necessarily non-deterministic and require advanced experimental techniques such as noiseless amplification. Recently it was shown that the benefits of noiseless amplification could be extracted by performing a post-selective filtering of the measurement record to improve the performance of quantum key distribution. We apply this protocol to entanglement degraded by transmission loss of up to the equivalent of 100km of optical fibre. We measure an effective entangled resource stronger than that achievable by even a maximally entangled resource passively transmitted through the same channel. We also provide a proof-of-principle demonstration of secret key extraction from an otherwise insecure regime. The measurement-based noiseless linear amplifier offers two advantages over its physical counterpart: ease of implementation and near optimal probability of success. It should provide an effective and versatile tool for a broad class of entanglement-based quantum communication protocols.The impossibility of determining all properties of a system, as exemplified by Heisenberg's uncertainty principle [1] is a well known signature of quantum mechanics. It results in phase and amplitude fluctuations in the vacuum, enables applications such as quantum key distribution and is at the heart of fundamental results such as the no-cloning theorem [2], quantum limited metrology [3], and the unavoidable addition of noise during amplification [4,5]. This last constraint means even an ideal quantum amplifier cannot be used for entanglement distillation [6][7][8] which is a critical step in the creation of large scale quantum information networks [9,10].Distillation protocols, originally conceived for discrete variables [6,7], proved initially more elusive in the continuous variable (CV) regime. The most experimentally feasible, and theoretically well studied, class of CV states and operations are the Gaussian states and the operations that preserve their Gaussianity [11]. Protocols that distill Gaussian states were discovered [8,12] involving an initial non-Gaussian operation that increases the entanglement followed by a 'Gaussification' step that iteratively drives the output towards a Gaussian state. More recently noiseless linear amplification has been identified as a simpler method of distilling Gaussian entanglement [13][14][15].The noiseless linear amplifier (NLA) avoids the unavoidable noise penalty by moving to a non-deterministic protocol. This ingenious concept and a linear optics implementation have been proposed [13,16,17] and experimentally realised for the case of amplifying coherent states [18][19][20][21], qubits [22][23][24], and the concentration of phase information [25]. All of these were extremely challenging experiments, with only Ref.[18] demonstrating entanglement distillation and none directly showing an increase in Einstein-Podolsky-Rosen (EPR) correlations [26]. Moreover the succe...

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“…For Gaussian states, an NLA can, in principle, probabilistically increase the signal-to-noise ratio by increasing the mean values of the quadratures while keeping their variances at the initial level [38,[45][46][47][48]. The amplification can be described by an operatorĈ = gn, wheren is the number operator in the Fock basis.…”

Section: Noiseless Linear Amplifiermentioning

confidence: 99%

Noiseless Linear Amplifiers in Entanglement-Based Continuous-Variable Quantum Key Distribution

Zhang

Weedbrook³

et al. 2015

Entropy

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We propose a method to improve the performance of two entanglement-based continuous-variable quantum key distribution protocols using noiseless linear amplifiers. The two entanglement-based schemes consist of an entanglement distribution protocol with an untrusted source and an entanglement swapping protocol with an untrusted relay. Simulation results show that the noiseless linear amplifiers can improve the performance of these two protocols, in terms of maximal transmission distances, when we consider small amounts of entanglement, as typical in realistic setups.

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Nondeterministic noiseless amplification via non-symplectic phase space transformations

Cited by 28 publications

References 54 publications

Simulation of Gaussian channels via teleportation and error correction of Gaussian states

Simulation of Gaussian channels via teleportation and error correction of Gaussian states

Measurement-based noiseless linear amplification for quantum communication

Noiseless Linear Amplifiers in Entanglement-Based Continuous-Variable Quantum Key Distribution

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