Complete Characterization of Quantum-Optical Processes

Lobino, Mirko; Korystov, Dmitry; Kupchak, Connor; Figueroa, Eden; Sanders, Barry C.; Lvovsky, A. I.

doi:10.1126/science.1162086

Cited by 146 publications

(184 citation statements)

References 24 publications

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“…With developing tools of continuous-wave quantumoptical state engineering [3] as well as state and process tomography [4], the performance requirements for homodyne detectors continue to increase. The design of HDs for time-domain quantum tomography [5][6][7] is based on four main performance criteria: a) high bandwidth and a flat amplification profile within that bandwidth; b) high ratio of the measured quantum noise over the electronic noise; c) high common mode rejection ratio (CMRR); d) quantum efficiency of the photodiodes.…”

Section: Introductionmentioning

confidence: 99%

Versatile wideband balanced detector for quantum optical homodyne tomography

Kumar

Barrios

MacRae

et al. 2012

Optics Communications

114

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We present a comprehensive theory and an easy to follow method for the design and construction of a wideband homodyne detector for time-domain quantum measurements. We show how one can evaluate the performance of a detector in a specific time-domain experiment based on electronic spectral characteristic of that detector. We then present and characterize a high-performance detector constructed using inexpensive, commercially available components such as low-noise high-speed operational amplifiers and high-bandwidth photodiodes. Our detector shows linear behavior up to a level of over 13 dB clearance between shot noise and electronic noise, in the range from DC to 100 MHz. The detector can be used for measuring quantum optical field quadratures both in the continuous-wave and pulsed regimes with pulse repetition rates up to about 250 MHz.

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Section: Introductionmentioning

confidence: 99%

Versatile wideband balanced detector for quantum optical homodyne tomography

Kumar

Barrios

MacRae

et al. 2012

Optics Communications

114

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“…Fully reconfigurable circuits, capable of implementing any unitary transformation on optical modes, are realisable with arrays of beamsplitters and phase shifters [11], which have been demonstrated on partially reconfigurable waveguide circuits [12,13]. With large scale single-photon and multi-photon interference verified for a predictable experiment, on a fully characterised circuit [14], a reasonable assumption is that quantum mechanics holds and the system maintains correct operation as the circuit is continuously reconfigured to implement a random unitary operation.Secondly, we determine that the most likely route to incorrect operation is the unwanted introduction of disarXiv:1311.2913v2 [quant-ph] …”

mentioning

confidence: 99%

On the experimental verification of quantum complexity in linear optics

Carolan¹,

et al. 2014

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The first quantum technologies to solve computational problems that are beyond the capabilities of classical computers are likely to be devices that exploit characteristics inherent to a particular physical system, to tackle a bespoke problem suited to those characteristics. Evidence implies that the detection of ensembles of photons, which have propagated through a linear optical circuit, is equivalent to sampling from a probability distribution that is intractable to classical simulation. However, it is probable that the complexity of this type of sampling problem means that its solution is classically unverifiable within a feasible number of trials, and the task of establishing correct operation becomes one of gathering sufficiently convincing circumstantial evidence. Here, we develop scalable methods to experimentally establish correct operation for this class of sampling algorithm, which we implement with two different types of optical circuits for 3, 4, and 5 photons, on Hilbert spaces of up to 50, 000 dimensions. With only a small number of trials, we establish a confidence > 99% that we are not sampling from a uniform distribution or a classical distribution, and we demonstrate a unitary specific witness that functions robustly for small amounts of data. Like the algorithmic operations they endorse, our methods exploit the characteristics native to the quantum system in question. Here we observe and make an application of a "bosonic clouding" phenomenon, interesting in its own right, where photons are found in local groups of modes superposed across two locations. Our broad approach is likely to be practical for all architectures for quantum technologies where formal verification methods for quantum algorithms are either intractable or unknown.The construction of a universal quantum computer, capable of implementing any quantum computation or quantum simulation, is a major long term experimental objective. However, it is expected that non-universal quantum machines, that exploit characteristics of their own physical system to solve specific problems, will outperform classical computers in the near-term [1]. Ensembles of single photons in linear optical circuits are a recently proposed example: despite being non-interacting particles, their detection statistics are described by functions that are intractable to classical computers -matrix permanents [2]. It is therefore believed that linear optics constitutes a platform for the efficient sampling of probability distributions that cannot be simulated by classical computers, with strong evidence provided in the case of circuits described by large random matrices [3][4][5][6][7].A universal quantum computer, running for example Shor's factoring algorithm [8], creates an exponentially large probability distribution with individual peaks at highly regular intervals that facilitate the solution to the factoring problem allowing efficient classical verification, as is the case for all problems in the NP complexity class [9]. Accordingly, correct operation of the...

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“…This is particularly relevant for continuous variable quantum process tomography [3,4,[27][28][29][30], which aims at characterization of quantum operations on modes of quantized electromagnetic fields. Here, the most natural and readily available probe states are represented by coherent states |α , and the output states can be conveniently measured with homodyne detectors [6,8].…”

Section: Introductionmentioning

confidence: 99%

Continuous-variable quantum process tomography with squeezed-state probes

Fiurášek¹

2015

Phys. Rev. A

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We propose a procedure for tomographic characterization of continuous variable quantum operations which employs homodyne detection and single-mode squeezed probe states with a fixed degree of squeezing and anti-squeezing and a variable displacement and orientation of squeezing ellipse. Density matrix elements of a quantum process matrix in Fock basis can be estimated by averaging well behaved pattern functions over the homodyne data. We show that this approach can be straightforwardly extended to characterization of quantum measurement devices. The probe states can be mixed, which makes the proposed procedure feasible with current technology.

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Complete Characterization of Quantum-Optical Processes

Cited by 146 publications

References 24 publications

Versatile wideband balanced detector for quantum optical homodyne tomography

Versatile wideband balanced detector for quantum optical homodyne tomography

On the experimental verification of quantum complexity in linear optics

Continuous-variable quantum process tomography with squeezed-state probes

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