## A quantum pulse gate based on spectrally engineered sum frequency generation |

Optics Express, Vol. 19, Issue 15, pp. 13770-13778 (2011)

http://dx.doi.org/10.1364/OE.19.013770

Acrobat PDF (2242 KB)

### Abstract

We introduce the concept of a quantum pulse gate (QPG), a method for accessing the intrinsic broadband spectral mode structure of ultrafast quantum states of light. This mode structure can now be harnessed for applications in quantum information processing. We propose an implementation in a PPLN waveguide, based on spectrally engineered sum frequency generation (SFG). It allows us to pick well-defined spectral broadband modes from an ultrafast multi-mode state for interconversion to a broadband mode at another frequency. By pulse-shaping the bright SFG pump beam, different orthogonal broadband modes can be addressed individually and extracted with high fidelity.

© 2011 OSA

## 1. Introduction

1. A. R. Dixon, Z. L. Yuan, J. F. Dynes, A. W. Sharpe, and A. J. Shields, “Continuous operation of high bit rate quantum key distribution,” Appl. Phys. Lett. **96**, 161102 (2010). [CrossRef]

2. V. Giovannetti, S. Lloyd, and L. Maccone, “Quantum-enhanced positioning and clock synchronization,” Nature **412**, 417–419 (2001). [CrossRef] [PubMed]

3. U. M. Titulaer and R. J. Glauber, “Density operators for coherent fields,” Phys. Rev. **145**, 1041–1050 (1966). [CrossRef]

4. C. K. Law, I. A. Walmsley, and J. H. Eberly, “Continuous frequency entanglement: effective finite Hilbert space and entropy control,” Phys. Rev. Lett. **84**, 5304–5307 (2000). [CrossRef] [PubMed]

5. R. V. Roussev, C. Langrock, J. R. Kurz, and M. M. Fejer, “Periodically poled lithium niobate waveguide sum-frequency generator for efficient single-photon detection at communication wavelengths,” Opt. Lett. **29**, 1518–1520 (2004). [CrossRef] [PubMed]

12. H. J. McGuinness, M. G. Raymer, C. J. McKinstrie, and S. Radic, “Quantum frequency translation of single-photon states in a photonic crystal fiber,” Phys. Rev. Lett. **105**, 093604 (2010). [CrossRef] [PubMed]

13. W. P. Grice, A. B. U’Ren, and I. A. Walmsley, “Eliminating frequency and space-time correlations in multiphoton states,” Phys. Rev. A **64**, 063815 (2001). [CrossRef]

16. M. Raymer, S. van Enk, C. McKinstrie, and H. McGuinness, “Interference of two photons of different color,” Opt. Comm. **283**, 747–752 (2010). [CrossRef]

17. A. Pe’er, B. Dayan, A. A. Friesem, and Y. Silberberg, “Temporal shaping of entangled photons,” Phys. Rev. Lett. **94**, 073601 (2005). [CrossRef] [PubMed]

18. D. Kielpinski, J. F. Corney, and H. M. Wiseman, “Quantum optical waveform conversion,” Phys. Rev. Lett. **106**, 130501 (2011). [CrossRef] [PubMed]

19. C. Clausen, I. Usmani, F. Bussieres, N. Sangouard, M. Afzelius, H. D. Riedmatten, and N. Gisin, “Quantum storage of photonic entanglement in a crystal,” Nature **469**, 508–511 (2011). [CrossRef] [PubMed]

20. E. Saglamyurek, N. Sinclair, J. Jin, J. A. Slater, D. Oblak, F. Bussieres, M. George, R. Ricken, W. Sohler, and W. Tittel, “Broadband waveguide quantum memory for entangled photons,” Nature **469**, 512–515 (2011). [CrossRef] [PubMed]

22. P. P. Rohde, W. Mauerer, and C. Silberhorn, “Spectral structure and decompositions of optical states, and their applications,” New J. Phys. **9**, 010091 (2007). [CrossRef]

23. A. M. Branczyk, T. C. Ralph, W. Helwig, and C. Silberhorn, “Optimized generation of heralded fock states using parametric down-conversion,” New J. Phys. **12**, 063001 (2010). [CrossRef]

23. A. M. Branczyk, T. C. Ralph, W. Helwig, and C. Silberhorn, “Optimized generation of heralded fock states using parametric down-conversion,” New J. Phys. **12**, 063001 (2010). [CrossRef]

24. K. Laiho, K. N. Cassemiro, and C. Silberhorn, “Producing high fidelity single photons with optimal brightness via waveguided parametric down-conversion,” Opt. Express **17**, 22823–22837 (2009). [CrossRef]

25. H. P. Yuen and V. W. S. Chan, “Noise in homodyne and heterodyne detection,” Opt. Lett. **8**, 177–179 (1983). [CrossRef] [PubMed]

26. B. L. Schumaker, “Noise in homodyne detection,” Opt. Lett. **9**, 189–191 (1984). [CrossRef] [PubMed]

27. J. Leach, M. J. Padgett, S. M. Barnett, S. Franke-Arnold, and J. Courtial, “Measuring the orbital angular momentum of a single photon,” Phys. Rev. Lett. **88**, 257901 (2002). [CrossRef] [PubMed]

30. T. Yarnall, A. F. Abouraddy, B. E. A. Saleh, and M. C. Teich, “Synthesis and analysis of entangled photonic qubits in spatial-parity space,” Phys. Rev. Lett. **99**, 250502 (2007). [CrossRef]

*χ*

^{(2)}-nonlinear material. Well known in classical nonlinear optics, in recent years it has seen increasing adoption in quantum optics for efficient NIR single photon detection [5

5. R. V. Roussev, C. Langrock, J. R. Kurz, and M. M. Fejer, “Periodically poled lithium niobate waveguide sum-frequency generator for efficient single-photon detection at communication wavelengths,” Opt. Lett. **29**, 1518–1520 (2004). [CrossRef] [PubMed]

8. S. Tanzilli, W. Tittel, M. Halder, O. Alibart, P. Baldi, N. Gisin, and H. Zbinden, “A photonic quantum information interface,” Nature **437**, 116–120 (2005). [CrossRef] [PubMed]

9. A. P. VanDevender and P. G. Kwiat, “High-speed transparent switch via frequency upconversion,” Opt. Express **15**, 4677–4683 (2007). [CrossRef] [PubMed]

10. O. Kuzucu, F. N. C. Wong, S. Kurimura, and S. Tovstonog, “Joint temporal density measurements for two-photon state characterization,” Phys. Rev. Lett. **101**, 153602 (2008). [CrossRef] [PubMed]

11. H. Takesue, “Erasing distinguishability using quantum frequency up-conversion,” Phys. Rev. Lett. **101**, 173901 (2008). [CrossRef] [PubMed]

12. H. J. McGuinness, M. G. Raymer, C. J. McKinstrie, and S. Radic, “Quantum frequency translation of single-photon states in a photonic crystal fiber,” Phys. Rev. Lett. **105**, 093604 (2010). [CrossRef] [PubMed]

13. W. P. Grice, A. B. U’Ren, and I. A. Walmsley, “Eliminating frequency and space-time correlations in multiphoton states,” Phys. Rev. A **64**, 063815 (2001). [CrossRef]

15. P. J. Mosley, J. S. Lundeen, B. J. Smith, P. Wasylczyk, A. B. U’Ren, C. Silberhorn, and I. A. Walmsley, “Heralded generation of ultrafast single photons in pure quantum states,” Phys. Rev. Lett. **100**, 133601 (2008). [CrossRef] [PubMed]

16. M. Raymer, S. van Enk, C. McKinstrie, and H. McGuinness, “Interference of two photons of different color,” Opt. Comm. **283**, 747–752 (2010). [CrossRef]

## 2. SFG in terms of broadband modes

**a**’ to mode ’

**c**’ is given by analogous to the pulse-pumped SPDC Hamiltonian derived in [31

31. W. P. Grice and I. A. Walmsley, “Spectral information and distinguishability in type-ii down-conversion with a broadband pump,” Phys. Rev. A **56**, 1627–1634 (1997). [CrossRef]

*χ*

^{(2)}denoting the second order nonlinear polarization tensor element of the SFG process and

*P*the gating pulse power. The normalized SFG transfer function

*f*(

*ω*,

_{i}*ω*) ∝

_{o}*α*(

*ω*–

_{o}*ω*) × Φ(

_{i}*ω*,

_{o}*ω*) maps the input frequencies

_{i}*ω*to the sum frequencies

_{i}*ω*, where

_{o}*α*is the spectral amplitude of the classical gating pulse. The phase matching distribution of the SFG process Φ emerges from integrating the spatial part of the fields’ phases over the interaction length

*k*,

_{i}*k*,

_{o}*k*the dispersion relations of the input, output and gating field respectively.

_{g}**A**

*= ∫*

_{j}*dω*

*φ*(

_{j}*ω*)

**a**(

*ω*) and

**C**

*= ∫*

_{j}*d*

*ω ψ*(

_{j}*ω*)

**c**(

*ω*) corresponding to the Schmidt bases, the effective Hamiltonian from Eq. (1) can be rewritten as

**H**

_{BS}=

*θ*

**ac**

^{†}+ h. c. [32

32. S. Prasad, M. O. Scully, and W. Martienssen, “A quantum description of the beam splitter,” Opt. Comm. **62**, 139–145 (1987). [CrossRef]

**A**

*→ cos(*

_{j}*θ*)

_{j}**A**

*+*

_{j}*l*sin(

*θ*)

_{j}**C**

*. The effective coupling constant*

_{j}**C**

*if it initially has been in mode*

_{j}**A**

*– is*

_{j}*η*= sin

_{j}^{2}(

*θ*).

_{j}*f*(

*ω*,

_{i}*ω*)(Fig. 2 A1) exhibits spectral correlations, causing more than one non-zero Schmidt coefficient (Fig. 2 B1). This leads to the simultaneous conversion of multiple modes

_{o}**A**

*at once with non-zero coupling constants*

_{j}*P*(Fig. 2 C1). Hence a SFG process in general is not mode-selective.

## 3. The quantum pulse gate

*κ*≈ 1 with all others close to zero and a separable transfer function

_{j}*f*(

*ω*,

_{i}*ω*) ≈

_{o}*κ*

_{j}*φ*(

_{j}*ω*)

_{i}*ψ*(

_{j}*ω*). Also, now the full coupling

_{o}*θ*≈

_{j}*θ*is exploited, allowing for relatively weak gating beams for maximum conversion efficiency. We achieve this by engineering the SFG process such that the input beam group velocity

**A**

*,*

_{k}**H**

_{QPG}] = 0 where

*k*≠

*j*. In other words, the quantum pulse gate is mode-selective and accepts only mode

**A**

*for up-conversion.*

_{j}**U**

_{QPG}= 𝒯

*e*

^{−l ∫dtĤ(t)}is the unitary time evolution operator generated by the Hamiltonian operator

**Ĥ**(

*t*) that describes traversal of the pulse gate implementation, with 𝒯 the time ordering operator. It accurately describes the interplay between the frequency upconversion and its reverse process for an arbitrary pump power and coupling constant

*θ*. In the perturbative case with

*θ*≪ 1,

**U**

_{QPG}can be developed to first order and time ordering has no effect. For the higher order terms though, time ordering has to be applied to account for interaction between multiple photon conversions at the same time which results in spectral mode distortions in the strongly coupled regime. However, it has been shown that for any frequency conversion process described by a Bogoliubov transformation there exists a Bloch-Messiah reduction into orthogonal, independent processes. The mode structure coincides with the Schmidt decomposition from Eq. (2) in the weak coupling limit, but the spectral modes do not change dramatically for stronger coupling [33

33. W. Wasilewski, A. I. Lvovsky, K. Banaszek, and C. Radzewicz, “Pulsed squeezed light: Simultaneous squeezing of multiple modes,” Phys. Rev. A **73**, 063819 (2006). [CrossRef]

18. D. Kielpinski, J. F. Corney, and H. M. Wiseman, “Quantum optical waveform conversion,” Phys. Rev. Lett. **106**, 130501 (2011). [CrossRef] [PubMed]

**U**

_{QPG}≈

*e*

^{−lHQPG}.

*u*

_{0}(i. e. a Gaussian spectrum, Fig. 2 A2-C2) selects input mode

**A**

_{0}, gating with mode

*u*

_{1}(Fig. 2 A3-C3) selects

**A**

_{1}from the input pulse for frequency up-conversion. Because of the horizontal phasematching, the target mode is always the Gaussian pulse

**C**

_{0}regardless which spectral gating mode

*u*is used.

_{j}*χ*

^{(2)}-nonlinear medium into one horizontally polarized signal and one vertically polarized idler photon. For a collinear type-II PDC source pumped by ultrafast pulses the general effective Hamiltonian in terms of broadband modes reads We feed the signal photon (containing all broadband modes

**Ã**

*) from the PDC source into the QPG which is mode-matched such that*

_{j}**Ã**

_{0}=

**A**

_{0}. We note that for heralding pure single photons or pure Fock states [22

22. P. P. Rohde, W. Mauerer, and C. Silberhorn, “Spectral structure and decompositions of optical states, and their applications,” New J. Phys. **9**, 010091 (2007). [CrossRef]

**A**

*→*

_{j}**A**

*for*

_{j}*j*> 0. We choose the gating pulse power such that

**C**

_{0}is centered at the sum frequency of input and gating pulse, it can be split off easily into a separate beam path with a dichroic mirror. Conditioning on single photon events on the path of

**C**

_{0}provides us with pure heralded single photons in mode

**B**

_{0}. Fig. 3 illustrates this scheme: A photon detection event heralds a pure single photon pulse in broadband mode

*u*

_{1}. This process can be cascaded to successively pick off several modes

**A**

*from the input beam. Note that if we insert a mode matched QPG into the vertically polarized PDC beam to convert*

_{j}**B**

_{0}into

**D**

_{0}, we can unconditionally single out an ultrafast two-mode squeezed vacuum state from a multi-mode squeezer [33

33. W. Wasilewski, A. I. Lvovsky, K. Banaszek, and C. Radzewicz, “Pulsed squeezed light: Simultaneous squeezing of multiple modes,” Phys. Rev. A **73**, 063819 (2006). [CrossRef]

34. A. Eckstein, A. Christ, P. J. Mosley, and C. Silberhorn, “Highly efficient single-pass source of pulsed single-mode twin beams of light,” Phys. Rev. Lett. **106**, 013603 (2011). [CrossRef] [PubMed]

## 4. Experimental parameters

_{3}(Ti:PPLN) waveguide [35

35. S. Tanzilli, W. Tittel, H. De Riedmatten, H. Zbinden, P. Baldi, M. DeMicheli, D. Ostrowsky, and N. Gisin, “PPLN waveguide for quantum communication,” Eur. Phys. J. D **18**, 155–160 (2002). [CrossRef]

*μ*m × 5

*μ*m and

*L*= 50mm length. We employ a standard finite element method to calculate the spatial mode fields inside the waveguide and obtain their corresponding effective refractive indices which evaluate to

*μ*m poling period and is heated to 190°C to achieve phasematching for SFG of an input pulse at 1550nm to 557nm. The gating beam is ordinarily polarized, while input and output beam are extraordinarily polarized.

*ω*

_{0}and spectral standard deviation

*σ*travelling through a crystal of length

*L*with the propagation constant

*k*(

*ω*) will in first order approximation elongate by a factor

18. D. Kielpinski, J. F. Corney, and H. M. Wiseman, “Quantum optical waveform conversion,” Phys. Rev. Lett. **106**, 130501 (2011). [CrossRef] [PubMed]

*θ*≪ 1), as well as the impact of mode matching. For the given material parameters, we employ gating pulses with pulse form

*u*

_{0}to

*u*

_{10}, determine the Schmidt decomposition of the resulting transfer function

*f*(

*ω*,

_{i}*ω*), and plot the fidelity of a certain mode conversion, that is the overlap of the predominant QPG Schmidt function

_{o}*φ*(

_{j}*κ*≈ 1) with a Hermitian input mode

_{j}*ũ*from an incident light pulse. On the left, gating and input pulse have equal frequency FWHM, which is essential for good mode matching. Now, by switching the order

_{l}*j*of the gating mode (and without changing the physical parameters of the QPG), we select with high fidelity only the input mode

*j*to be converted. For

*j*≤ 10, the overlap

*φ*and input modes

_{j}*ũ*appear: A wide range of modes is converted for any given input spectrum. The checkerboard pattern reflects the fact that only modes of the same parity exhibit an overlap, an odd and an even mode are orthogonal regardless of mode-matching.

_{l}## 5. Conclusion and outlook

1. A. R. Dixon, Z. L. Yuan, J. F. Dynes, A. W. Sharpe, and A. J. Shields, “Continuous operation of high bit rate quantum key distribution,” Appl. Phys. Lett. **96**, 161102 (2010). [CrossRef]

2. V. Giovannetti, S. Lloyd, and L. Maccone, “Quantum-enhanced positioning and clock synchronization,” Nature **412**, 417–419 (2001). [CrossRef] [PubMed]

## Acknowledgments

^{2}for fruitful discussions and Michael Raymer for valuable input. We acknowledge support of this work under the EC grant agreement CORNER ( FP7-ICT-213681).

## References and links

1. | A. R. Dixon, Z. L. Yuan, J. F. Dynes, A. W. Sharpe, and A. J. Shields, “Continuous operation of high bit rate quantum key distribution,” Appl. Phys. Lett. |

2. | V. Giovannetti, S. Lloyd, and L. Maccone, “Quantum-enhanced positioning and clock synchronization,” Nature |

3. | U. M. Titulaer and R. J. Glauber, “Density operators for coherent fields,” Phys. Rev. |

4. | C. K. Law, I. A. Walmsley, and J. H. Eberly, “Continuous frequency entanglement: effective finite Hilbert space and entropy control,” Phys. Rev. Lett. |

5. | R. V. Roussev, C. Langrock, J. R. Kurz, and M. M. Fejer, “Periodically poled lithium niobate waveguide sum-frequency generator for efficient single-photon detection at communication wavelengths,” Opt. Lett. |

6. | M. A. Albota and F. N. C. Wong, “Efficient single-photon counting at 1.55 ţm by means of frequency upconversion,” Opt. Lett. |

7. | A. P. Vandevender and P. G. Kwiat, “High efficiency single photon detection via frequency up-conversion,” J. Mod. Opt. |

8. | S. Tanzilli, W. Tittel, M. Halder, O. Alibart, P. Baldi, N. Gisin, and H. Zbinden, “A photonic quantum information interface,” Nature |

9. | A. P. VanDevender and P. G. Kwiat, “High-speed transparent switch via frequency upconversion,” Opt. Express |

10. | O. Kuzucu, F. N. C. Wong, S. Kurimura, and S. Tovstonog, “Joint temporal density measurements for two-photon state characterization,” Phys. Rev. Lett. |

11. | H. Takesue, “Erasing distinguishability using quantum frequency up-conversion,” Phys. Rev. Lett. |

12. | H. J. McGuinness, M. G. Raymer, C. J. McKinstrie, and S. Radic, “Quantum frequency translation of single-photon states in a photonic crystal fiber,” Phys. Rev. Lett. |

13. | W. P. Grice, A. B. U’Ren, and I. A. Walmsley, “Eliminating frequency and space-time correlations in multiphoton states,” Phys. Rev. A |

14. | A. B. U’Ren, C. Silberhorn, K. Banaszek, I. A. Walmsley, R. Erdmann, W. P. Grice, and M. G. Raymer, “Generation of pure-state single-photon wavepackets by conditional preparation based on spontaneous parametric downconversion,” Laser Phys. |

15. | P. J. Mosley, J. S. Lundeen, B. J. Smith, P. Wasylczyk, A. B. U’Ren, C. Silberhorn, and I. A. Walmsley, “Heralded generation of ultrafast single photons in pure quantum states,” Phys. Rev. Lett. |

16. | M. Raymer, S. van Enk, C. McKinstrie, and H. McGuinness, “Interference of two photons of different color,” Opt. Comm. |

17. | A. Pe’er, B. Dayan, A. A. Friesem, and Y. Silberberg, “Temporal shaping of entangled photons,” Phys. Rev. Lett. |

18. | D. Kielpinski, J. F. Corney, and H. M. Wiseman, “Quantum optical waveform conversion,” Phys. Rev. Lett. |

19. | C. Clausen, I. Usmani, F. Bussieres, N. Sangouard, M. Afzelius, H. D. Riedmatten, and N. Gisin, “Quantum storage of photonic entanglement in a crystal,” Nature |

20. | E. Saglamyurek, N. Sinclair, J. Jin, J. A. Slater, D. Oblak, F. Bussieres, M. George, R. Ricken, W. Sohler, and W. Tittel, “Broadband waveguide quantum memory for entangled photons,” Nature |

21. | M. Martinelli, N. Treps, S. Ducci, S. Gigan, A. Maître, and C. Fabre, “Experimental study of the spatial distribution of quantum correlations in a confocal optical parametric oscillator,” Phys. Rev. A |

22. | P. P. Rohde, W. Mauerer, and C. Silberhorn, “Spectral structure and decompositions of optical states, and their applications,” New J. Phys. |

23. | A. M. Branczyk, T. C. Ralph, W. Helwig, and C. Silberhorn, “Optimized generation of heralded fock states using parametric down-conversion,” New J. Phys. |

24. | K. Laiho, K. N. Cassemiro, and C. Silberhorn, “Producing high fidelity single photons with optimal brightness via waveguided parametric down-conversion,” Opt. Express |

25. | H. P. Yuen and V. W. S. Chan, “Noise in homodyne and heterodyne detection,” Opt. Lett. |

26. | B. L. Schumaker, “Noise in homodyne detection,” Opt. Lett. |

27. | J. Leach, M. J. Padgett, S. M. Barnett, S. Franke-Arnold, and J. Courtial, “Measuring the orbital angular momentum of a single photon,” Phys. Rev. Lett. |

28. | N. Treps, N. Grosse, W. P. Bowen, C. Fabre, H.-A. Bachor, and P. K. Lam, “A quantum laser pointer,” Science |

29. | M. Lassen, V. Delaubert, J. Janousek, K. Wagner, H.-A. Bachor, P. K. Lam, N. Treps, P. Buchhave, C. Fabre, and C. C. Harb, “Tools for multimode quantum information: modulation, detection, and spatial quantum correlations,” Phys. Rev. Lett. |

30. | T. Yarnall, A. F. Abouraddy, B. E. A. Saleh, and M. C. Teich, “Synthesis and analysis of entangled photonic qubits in spatial-parity space,” Phys. Rev. Lett. |

31. | W. P. Grice and I. A. Walmsley, “Spectral information and distinguishability in type-ii down-conversion with a broadband pump,” Phys. Rev. A |

32. | S. Prasad, M. O. Scully, and W. Martienssen, “A quantum description of the beam splitter,” Opt. Comm. |

33. | W. Wasilewski, A. I. Lvovsky, K. Banaszek, and C. Radzewicz, “Pulsed squeezed light: Simultaneous squeezing of multiple modes,” Phys. Rev. A |

34. | A. Eckstein, A. Christ, P. J. Mosley, and C. Silberhorn, “Highly efficient single-pass source of pulsed single-mode twin beams of light,” Phys. Rev. Lett. |

35. | S. Tanzilli, W. Tittel, H. De Riedmatten, H. Zbinden, P. Baldi, M. DeMicheli, D. Ostrowsky, and N. Gisin, “PPLN waveguide for quantum communication,” Eur. Phys. J. D |

**OCIS Codes**

(270.0270) Quantum optics : Quantum optics

(190.4223) Nonlinear optics : Nonlinear wave mixing

**ToC Category:**

Quantum Optics

**History**

Original Manuscript: April 8, 2011

Revised Manuscript: May 19, 2011

Manuscript Accepted: June 13, 2011

Published: July 5, 2011

**Citation**

Andreas Eckstein, Benjamin Brecht, and Christine Silberhorn, "A quantum pulse gate based on spectrally engineered sum frequency generation," Opt. Express **19**, 13770-13778 (2011)

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-19-15-13770

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### References

- A. R. Dixon, Z. L. Yuan, J. F. Dynes, A. W. Sharpe, and A. J. Shields, “Continuous operation of high bit rate quantum key distribution,” Appl. Phys. Lett. 96, 161102 (2010). [CrossRef]
- V. Giovannetti, S. Lloyd, and L. Maccone, “Quantum-enhanced positioning and clock synchronization,” Nature 412, 417–419 (2001). [CrossRef] [PubMed]
- U. M. Titulaer and R. J. Glauber, “Density operators for coherent fields,” Phys. Rev. 145, 1041–1050 (1966). [CrossRef]
- C. K. Law, I. A. Walmsley, and J. H. Eberly, “Continuous frequency entanglement: effective finite Hilbert space and entropy control,” Phys. Rev. Lett. 84, 5304–5307 (2000). [CrossRef] [PubMed]
- R. V. Roussev, C. Langrock, J. R. Kurz, and M. M. Fejer, “Periodically poled lithium niobate waveguide sum-frequency generator for efficient single-photon detection at communication wavelengths,” Opt. Lett. 29, 1518–1520 (2004). [CrossRef] [PubMed]
- M. A. Albota and F. N. C. Wong, “Efficient single-photon counting at 1.55 ţm by means of frequency upconversion,” Opt. Lett. 29, 1449–1451 (2004). [CrossRef] [PubMed]
- A. P. Vandevender and P. G. Kwiat, “High efficiency single photon detection via frequency up-conversion,” J. Mod. Opt. 51, 1433–1445 (2004).
- S. Tanzilli, W. Tittel, M. Halder, O. Alibart, P. Baldi, N. Gisin, and H. Zbinden, “A photonic quantum information interface,” Nature 437, 116–120 (2005). [CrossRef] [PubMed]
- A. P. VanDevender and P. G. Kwiat, “High-speed transparent switch via frequency upconversion,” Opt. Express 15, 4677–4683 (2007). [CrossRef] [PubMed]
- O. Kuzucu, F. N. C. Wong, S. Kurimura, and S. Tovstonog, “Joint temporal density measurements for two-photon state characterization,” Phys. Rev. Lett. 101, 153602 (2008). [CrossRef] [PubMed]
- H. Takesue, “Erasing distinguishability using quantum frequency up-conversion,” Phys. Rev. Lett. 101, 173901 (2008). [CrossRef] [PubMed]
- H. J. McGuinness, M. G. Raymer, C. J. McKinstrie, and S. Radic, “Quantum frequency translation of single-photon states in a photonic crystal fiber,” Phys. Rev. Lett. 105, 093604 (2010). [CrossRef] [PubMed]
- W. P. Grice, A. B. U’Ren, and I. A. Walmsley, “Eliminating frequency and space-time correlations in multiphoton states,” Phys. Rev. A 64, 063815 (2001). [CrossRef]
- A. B. U’Ren, C. Silberhorn, K. Banaszek, I. A. Walmsley, R. Erdmann, W. P. Grice, and M. G. Raymer, “Generation of pure-state single-photon wavepackets by conditional preparation based on spontaneous parametric downconversion,” Laser Phys. 15, 0611019 (2005).
- P. J. Mosley, J. S. Lundeen, B. J. Smith, P. Wasylczyk, A. B. U’Ren, C. Silberhorn, and I. A. Walmsley, “Heralded generation of ultrafast single photons in pure quantum states,” Phys. Rev. Lett. 100, 133601 (2008). [CrossRef] [PubMed]
- M. Raymer, S. van Enk, C. McKinstrie, and H. McGuinness, “Interference of two photons of different color,” Opt. Comm. 283, 747–752 (2010). [CrossRef]
- A. Pe’er, B. Dayan, A. A. Friesem, and Y. Silberberg, “Temporal shaping of entangled photons,” Phys. Rev. Lett. 94, 073601 (2005). [CrossRef] [PubMed]
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