Quantum Super-resolution Imaging in Fluorescence Microscopy

Dept. of Physics of Complex SystemsWeizmann Institute of Science, Israel

FRISNO 12, Ein Gedi (February 2013)

Osip Schwartz, Dan Oron, Jonathan M. Levitt, Ron Tenne, Stella Itzhakov and Dan Oron

Slide 2 of 18

Microscopy and resolution

Workarounds:•Nonlinear optical methods: use nonlinear optical response to produce narrower point spread function

•Stochastic methods: use fluorophores turning on and off randomly

•Quantum optics?

Resolution of far-field optical microscopes is limited by about half wavelength.(Ernst Abbe, 1873)

o Multi-photon interference Afek et al., Science 328 (2010) Walther et al., Nature 429 (2004)

o Entangled images Boyer et al., Science 321 (2008)o Sub shot noise imaging Brida et al., Nat. Photonics 4 (2010)o Resolution enhancement?

Slide 3 of 18

Object Light detecto

r

Imaging system

Quantum light

Quantum super-resolution

Kolobov, Fabre, PRL2000

Saleh et al., PRL 2005

M.Tsang PRL 2009

Shin et al., PRL 2011

Thiel et al., PRL 2007

Thiel et al., PRA 2009

Giovannetti, PRA 2009

Guerrieri et al., PRL 2010

• Quantum Limits on Optical Resolution

• Wolf equations for two-photon light

• Quantum Imaging beyond the Diffraction Limit by Optical Centroid Measurements

• Quantum spatial superresolution by optical centroid measurements

• Quantum imaging with incoherent photons,

• Sub-Rayleigh quantum imaging using single-photon sources

• Sub-Rayleigh-diffraction-bound quantum imaging,

• Sub-Rayleigh Imaging via N-Photon Detection,

Slide 4 of 18

Classical light

Quantum emitters

Light detector

Imaging system

Quantum light

Quantum emitters

S.W. Hell et al., Bioimaging (1995)

What if we had an emitter that would always emit photon pairs?

Slide 5 of 18

Multi-photon detection microscopy

Spatial distribution of photon pairs carries high spatial frequency information (up to double resolution)

cascaded emitters

Photon pair detector

Imaging system

Photon pairτ1

τ2

τ1>>τ2

Point spread function: h2phot(x) = h2(x)

Similarly, in N-photon detection microscopy hNphot(x) = hN(x)

Slide 6 of 18

Antibunching microscopy

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Instead of actual photon pairs, consider ‘missing’ pairs.

Fluorescence intensity autocorrelation g(2)

10 μs interval between pulses

Number of photons emitted after excitation:Organic dyes: W. Ambrose et al. (1997)

Quantum dots: B. Lounis et al. (2000).

NV centers: R. Brouri et al. (2000).

Observations of antibunching:

Slide 7 of 18

Antibunching-induced correlations

Two adjacent detectors in the image plane:

x0

For individual fluorophore:For individual fluorophore:

Sum over fluorophores

For multiple fluorophores:For multiple fluorophores:

Slide 8 of 18

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Wavelength, nm

EmittersFluorescence saturation

Schwartz et al.,ACS Nano 6 (2012)

CdSe / ZnSe / ZnS quantum dots

Slide 9 of 18

At 1 kHz:

Schwartz et al.,ACS Nano 6 (2012)

Slide 10 of 18

Photon counting with a CCD

threshold

Dark counts

Less noiseMore signal

Read noisePixel signal distribution

CCD ADC units

arXiv:1212.6003

Slide 11 of 18

Computing correlations

• compute correlations for all pixel configurations

• Fourier-interpolate the resulting images

• Sum the interpolated images

2nd order:

3rd order:

Quantifies the missing pairs

Missing 3-photon events (except those due to missing pairs, already accounted for)

arXiv:1212.6003

Slide 12 of 18

Antibunching with a CCD

Third order:g(3)(τ1, τ2)==<n(t)n(t+τ1)n(t+ τ2)>

Second order autocorrelation function:g(2)(τ)=<n(t)n(t+ τ)>

τ, ms τ, ms

τ1, ms τ1, ms

τ 2, m

sτ 2,

ms

Quantum dot Classical signal

arXiv:1212.6003

Slide 13 of 18 arXiv:1212.6003

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Slide 14 of 18 arXiv:1212.6003

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2nd order antibunching

Slide 15 of 18 arXiv:1212.6003

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Fluorescence image

2nd order antibunching

3rd order antibunching

Resolution: 271 nm FWHM

216 nm FWHM(x1.26)

181 nm FWHM(x1.50)

Slide 16 of 18

Optical sectioning

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Fluorescence imaging

2nd order antibunching

imaging

Defocused image of a quantum dot:

Optical signal integrated over the field of view:

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Defocusing, μm

Slide 17 of 18

Summary

•Far-field super-resolution imaging demonstrated by using quantum properties of light naturally present in fluorescence microscopy

•The experiment was performed with commercially available equipment, at room temperature, with commonly used quantum dot fluorophores

•With further development of detector technology, antibunching imaging may become feasible as a practical imaging method

Slide 18 of 18

The team

Jonathan M. Levitt

Dan Oron

Zvicka DeutschStella Itzhakov

Ron Tenne

Slide 19 of 18

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Slide 20 of 18

Superresolved images

Regular (photon counting) image Second order correlations Third order correlations

Reconstructed high resolution images

Slide 21 of 18

Superresolved images

arXiv:1212.6003

Slide 22 of 18

Superresolved images

Slide 23 of 18

Superresolved images

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PSF width (nm)

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PSF width (nm)

Slide 25 of 18

Quantum super-resolution

Conceptual difficulty: an absorptive grating with sub-wavelength period acts as an attenuator for every photon

• Transmitted light contains no information on the grating phase or period • Any linear absorber mask is a superposition of gratings• High spatial frequency components of the mask are lost