Quantum Process Tomography of an Optically-Controlled Kerr Non-linearity

Kupchak, Connor; Rind, Samuel; Jordaan, Bertus; Figueroa, Eden

doi:10.1038/srep16581

Cited by 10 publications

(6 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The polarization of each of the retrieved qubit states is obtained with the following procedure [24]: (a) measurement of the polarization of all the input states, (b) qubit storage experiment and determination of the output Stokes vectors (S out ), (c) rotation of input states to match the orthogonal axis of the normalized stored vectors (S in ) and (d) evaluation of the total fidelity using F = 1 2 (1 + S out · S in + (1 − S out · S out )(1 − S in · S in )). We obtained an average fidelity of 86.6±0.6%.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Ultralow-Noise Room-Temperature Quantum Memory for Polarization Qubits

et al. 2017

Self Cite

View full text Add to dashboard Cite

Here we show an ultra-low noise regime of operation in a simple quantum memory in warm 87 Rb atomic vapor. By modelling the quantum dynamics of four-level room temperature atoms, we achieve fidelities >90% for single-photon level polarization qubits, clearly surpassing any classical strategy exploiting the non-unitary memory efficiency. This is the first time such important threshold has been crossed with a room temperature device. Additionally we also show novel experimental techniques capable of producing fidelities close to unity. Our results demonstrate the potential of simple, resource-moderate experimental room temperature quantum devices.PACS numbers: 42.50. Ex, 42.50.Gy Robust and operational room temperature quantum devices are a fundamental cornerstone towards building quantum networks composed of a large number of lightmatter interfaces [1,2]. Such quantum networks will be the basis of the creation of quantum repeater networks [3] and measurement device independent quantum cryptography links [4,5]. Given the recent success in the creation of elementary playgrounds in which single photons interact with atoms in controlled low temperature environments [6][7][8][9][10], the next technological frontier is the design of interfaces where such phenomena can be performed without extra-cooling [11][12][13][14][15]. The big challenge for such room temperature operation is to defeat the inherent strong atomic motion, decoherence and a considerable amount of background photons present [16][17][18][19][20][21][22][23]. A pertinent metric of these effects is the SBR, defined as η/q, where η is the retrieved fraction of a single excitation stored in a quantum memory and q the average number of concurrently emitted photons due to background processes. Quantum memory setup and storage parameters optimization. Our experimental setup includes four aspects of utmost relevance in order to allow for high SBR and quantum memory fidelity at the single-photon level: a) Dual rail operation. We store pulses containing on average one qubit in warm 87 Rb vapor using electromagnetically induced transparency (EIT). Two independent control beams coherently prepare two volumes within a single 87 Rb vapor cell at 60 • C, containing Kr buffer gas, thus serving as the storage medium for each mode of a polarization qubit. We employed two externalcavity diode lasers phase-locked at 6.835 GHz. The probe field frequency is stabilized to the 5S 1/2 F = 1 → 5P 1/2 F = 1 transition at a wavelength of 795 nm (detuning ∆) while the control field interacts with the 5S 1/2 F = 2 → 5P 1/2 F = 1 transition. b) Control field suppression. Polarization elements supply 42 dB of control field attenuation (80% probe transmission) while two temperature-controlled etalon resonators (linewidths of 40 and 24 MHz) provide additional 102 dB. The total probe field transmission is 4.5% for all polarization inputs, exhibiting an effective, control/probe suppression ratio of 130 dB. c) Background/efficiency compromise. The storage efficiency and the number of ba...

show abstract

mentioning

confidence: 99%

“…Optimal qubit storage fidelities are obtained for non-maximal storage efficiency. A combination of these three techniques have been used in our previous investigation to obtain fidelities >75% with storage efficiencies ∼ 5% [24]. d) Probe temporal duration.…”

mentioning

confidence: 99%

Ultralow-Noise Room-Temperature Quantum Memory for Polarization Qubits

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…Such information can be extracted from the tensor elements mapping the input state density matrix to certain off-diagonal element of the output state. For example, the phase value the 𝜌 01 𝑜𝑢𝑡 element of the output state is determined by the phases Im{ln[𝜀 01 𝑚𝑛 ]} of 𝜀 01 𝑚𝑛 process tensor elements [45]. To elaborate this relation, we decompose the process 𝜀 into a phase shift superoperator and a phase-symmetric process 𝜀 ′ 𝜌 ̂𝑜𝑢𝑡 = 𝜀(𝜌 ̂𝑖𝑛 ) = 𝑈 ̂(𝜙)𝜀 ′ (𝜌 ̂𝑖𝑛 )𝑈 ̂ †(𝜙) = 𝑒 𝑖𝜙𝑎 ̂ †𝑎 ̂𝜀′ (𝜌 ̂𝑖𝑛 )𝑒 −𝑖𝜙𝑎 ̂ †𝑎 ̂, (8) where 𝜙 is a constant phase shift.…”

Section: Quantum Process Tomography Of Metal-hole Arraysmentioning

confidence: 99%

Quantum tomography of the photon-plasmon conversion process in a metal hole array

Tang¹,

Zheng²,

Guo³

et al. 2019

Opt. Express

View full text Add to dashboard Cite

In the past decades, quantum plasmonics has become an active area due to its potential applications in on-chip plasmonic devices for quantum information processing. However, the fundamental physical process, i.e., how a quantum state of light evolves in the photon-plasmon conversion process, has not been clearly understood. Here, we report a complete characterization of the plasmon-assisted extraordinary optical transmission process through quantum process tomography. By inputting various coherent states to interact with the plasmonic structure and detecting the output states with a homodyne detector, we reconstruct the process tensor of the photon-plasmon conversion process. Both the amplitude and phase information of the process are extracted, which explains the evolution of the quantum-optical state after the coupling with plasmons. Our experimental demonstration constitutes a fundamental block for future on-chip applications of quantum plasmonic circuits.

show abstract

“…However, further advancing quantum technologies requires improvements in the fidelities of basic operations. Consequently, more precise and efficient reconstruction and diagnostic tools for estimation of quantum states [5][6][7][8][9][10][11][12], processes [13][14][15][16][17][18][19][20], and measurements [21][22][23][24] are essential. Quantum tomographic techniques for optical quantum states of light have become standard tools because quantum light sources are essential for implementations of continuous-variable (CV) quantum computation and communication [25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Quadrature histograms in maximum-likelihood quantum state tomography

2018

View full text Add to dashboard Cite

Quantum state tomography aims to determine the quantum state of a system from measured data and is an essential tool for quantum information science. When dealing with continuous variable quantum states of light, tomography is often done by measuring the field amplitudes at different optical phases using homodyne detection. The quadrature-phase homodyne measurement outputs a continuous variable, so to reduce the computational cost of tomography, researchers often discretize the measurements. We show that this can be done without significantly degrading the fidelity between the estimated state and the true state. This paper studies different strategies for determining the histogram bin widths. We show that computation time can be significantly reduced with little loss in the fidelity of the estimated state when the measurement operators corresponding to each histogram bin are integrated over the bin width.

show abstract

Quantum Process Tomography of an Optically-Controlled Kerr Non-linearity

Cited by 10 publications

References 44 publications

Ultralow-Noise Room-Temperature Quantum Memory for Polarization Qubits

Ultralow-Noise Room-Temperature Quantum Memory for Polarization Qubits

Quantum tomography of the photon-plasmon conversion process in a metal hole array

Quadrature histograms in maximum-likelihood quantum state tomography

Contact Info

Product

Resources

About