Continuously active interferometer stabilization and control for time-bin entanglement distribution

Abstract

We describe a new method enabling continuous stabilization and fine-level phase control of time-bin entanglement interferometers. Using this technique we demonstrate entangled photon transmission through 50 km of standard single-mode fiber. This technique reuses the entangled-pair generation pump which is co-propagated with the transmitted entangled photons. The co-propagating pump adds minimal noise to the entangled photons which are characterized by measuring a two-photon interference fringe.

Loss resilience for two-qubit state transmission using distributed phase sensitive amplification

“…The classically measured loss of the 5-km DSF is 1.5 dB, of which approximately 0.2 dB is attributed to connector loss. The pump is spectrally demultiplexed after the analysis interferometers and used to lock the phase reference frame of both analysis interferometers to the source interferometer as described elsewhere 22 .…”

New quantum dialogue protocol based on continuous-variable two-mode squeezed vacuum states

“…6. By applying beam splitter BS 1 on entangled optical modes a * 21 and a 61 , the optical mode a 71 and a 81 will, respectively, turn out to be: X a 52 = √ η 2 X a 12 + 1 − η 2 X a 42 P a 52 = √ η 2 P a 12 + 1 − η 2 P a 42 X a 62 = √ η 2 X a 42 + 1 − η 2 X a 12 P a 62 = √ η 2 P a 42 + 1 − η 2 P a 12 (24) where η 2 is the transmission coefficient of beam splitter BS 2 . If Eve operates beam splitter BS 3 on the entangled optical modes a 81 and a 62 , then she will obtain the entangled optical modes a 91 and a 72 , respectively.…”

“…And continuous-variable quantum key distribution can resist many kinds of attacks, such as disturbance attack, manin-the-middle attack, entanglement-and-measure attack. Due to the advantages of continuous-variable quantum states, the continuous-variable quantum communication has attracted a lot of attention in both theoretical and experimental aspects in recent years [14][15][16][17][18][19][20][21][22][23][24][25]. Jouguet et al [14] overcame all previous limitations and demonstrated for the first time continuous-variable quantum key distribution over 80 km of optical fiber.…”

“…Toliver P et al described a new method enabling continuous stabilization and fine-level phase control of time-bin entanglement interferometers. Using this technique, they demonstrated entangled photon transmission through 50 km of standard single-mode fiber [24]. However, a mature QD protocol based on continuous-variable quantum states has been discussed seldom.…”

Active stabilization of a fiber-optic two-photon interferometer using continuous optical length control

“…In the case of a long-distance fiber-based quantum communication channel involving correlated single photons, the observation of the HOM fringe with high stability is difficult because a single photon of a two-photon wavepacket is considered to have a very short coherence length determined by the spectral bandwidth [10]. To overcome this issue, the optical path-lengths have to be actively stabilized within a single photon wavepacket [11][12][13][14][15]. Furthermore, multi-step control sequences should be employed to compensate the fiber path-length difference due to thermally induced high/low-speed longitudinal expansion of the single-mode fiber core.…”