State-independent quantum state tomography by photon-number-resolving measurements

Abstract

The Wigner quasiprobability distribution of a narrowband single-photon state was reconstructed by quantum state tomography using photon-number-resolving measurements with transition-edge sensors (TES) at system efficiency 58(2)%. This method makes no assumptions on the nature of the measured state, save for the limitation on photon flux imposed by the TES. Negativity of the Wigner function was observed in the raw data without any inference or correction for decoherence.

Non-Gaussian and Gottesman–Kitaev–Preskill state preparation by photon catalysis

“…Figure 2(b) demonstrates that when a | | 2 is the same fraction of the optimal value as in figure 2(a), but the detector is no longer perfect (η=0.9), the Wigner function has the same qualitative shape in each case but exhibits an overall decreased negativity due to the effective loss at the detector. When comparing to a typical experimental displacement such as using the beamsplitter parameter r 2 =0.97 [24] (black dotted-dashed line in figure 2(c)), the addition of even imperfect PNR detectors improves the attainable fidelity with the ideal displaced single-photon state.…”

“…It has been shown that GKP states could be probabilistically generated from squeezed Schrodinger cat states [19], and this process has been made deterministic [20]. Single-photon states, which have been generated and characterized using heralding detection of downconverted photon pairs [21][22][23][24], are excellent non-Gaussian ingredients. Sophisticated techniques, such as photon subtraction [25,26] and addition [27], have led to very promising advances.…”

Generalized overlap quantum state tomography1

“…ion [22], as well as on microwave cavity fields [23,24]. More recently, the coming of age of photon-number-resolving (PNR) detection [25] has opened the door to using the full WVBW method on traveling optical fields with no prior knowledge of the measured quantum state [26,27]. While the WVBW method presents clear advantages in terms of the numerical demands on reconstruction, it requires a phase-space raster scan involving a large number of optical displacements, and the pitch of the raster scan is determined by the specific features of the (unknown) Wigner function to be resolved.…”

“…The effect of known system losses can also be entirely deconvoluted from the measured density operator. We present the mathematical derivation of this generalized overlap quantum state tomography and present experimental results for a single-photon Fock state with performance that far exceeds that of the recent WVBW demonstration [27]. Furthermore, we can perform loss compensation in one fell swoop for the entire density matrix ρ, unlike at each experimental data point in the WVBW method.…”

“…Experimental implementation. The experimental setup was identical to our previous implementation of WVBW tomography [27] and is described in detail in the Supplemental Material [31]. It was based on a very stable CW Nd:YAG laser which provided all coherent states upon phase and amplitude modulations by a piezoelectric-actuated mirror and a homemade RbTiOAsO 4 electro-optic modulator, respectively.…”