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Two-photon interference of the emission from electrically tunable remote quantum dots


Self-assembled quantum dots comprise a versatile system with which to study quantum effects in the solid state. Many devices have been developed that demonstrate controlled charging of a quantum dot1, Rabi oscillations2, coherent spin control3 and electrically injected non-classical photon emission4. Often referred to as ‘artificial atoms’, quantum dots have discrete energy levels, making them a viable candidate for encoding qubits. However, unlike single atoms, no two quantum dots are alike. This is a complication for quantum-information applications that require qubits initialized in the same state and interactions between remote systems mediated by indistinguishable photons. We report that truly remote, independent, quantum dots can be tuned to the same energy using large applied electric fields. This allows two-photon interference5 of their emission under coincidence gating and opens up the possibility of transferring quantum information between remote solid-state sources.

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Figure 1: Design and spectral characteristics of the tunable source.
Figure 2: Experimental arrangement for two-photon interference.
Figure 3: Two-photon interference and Hanbury–Brown and Twiss results.


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This work was partly supported by the European Union through the Information Science Technologies Framework Program 6 Integrated Projects Qubit Applications (QAP, contract no. 015848; Q-ESSENCE, contract no. FP7/2007–2013). EPSRC provided support for R.B.P. and QIPIRC for C.A.N. We would also like to thank D. Granados and R. J. Young for useful discussions.

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I.F., C.A.N. and D.A.R. carried out MBE growth of the samples. R.B.P. fabricated the devices. R.B.P. and A.J.B. performed the experiments and data analysis. R.B.P. wrote the paper with input from A.J.B. and A.J.S. A.J.S. guided the work.

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Correspondence to Raj B. Patel.

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The authors declare no competing financial interests.

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Patel, R., Bennett, A., Farrer, I. et al. Two-photon interference of the emission from electrically tunable remote quantum dots. Nature Photon 4, 632–635 (2010).

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