Outlooks

1. Controlled entanglement swapping with telecom entanglement.

We will evaluate the performance of this concept in an extended version of the existing quantum network testbed connecting BNL and SBU. We aim to perform optically-controlled entanglement swapping (schematic depicted in the inset of Fig. 12). This extension and its proof of concept for quantum networking experiments is one of the main tasks of the proposed additional work. We will equip three substations (fiber exchange points) with optical control switches in order to allow for entanglement distribution and detection in the network.

  • Substation 1 will be located in the Communications Engineering building (ECC) in SBU, equipped with a portable entangled source and two frequency conversion unitssee Substation1 in Fig. 12 for physical location in the SBU campus).. We estimate a entangled pair production ratio of 104 ebits/sec and a 22dB loss in the SBU-BNL fiber connection.
  • Substation 2 will be located in the Scientific Data and Computation Center (SDCC) in the ITD building at BNL, equipped with a telecom Bell state measurement setup (see Substation 2 in Fig. 12 for the physicallocation in the BNL campus) , using nano-wire single photon counters for minimal dark counts of less that one per second.
  • Substation 3 will be located in Long Island Data center co-location facility at 71 Clinton Road in Garden City, NY, equipped with a portable memory-compatible telecom entanglement source see Substation 3 inFig. 12 for physical location on Long Island).. We estimate an entangled pair production ratio of 105 ebits/sec and a 30dB loss in the Garden City-BNL fiber connection.
  • Final Node A will be located in the CEWIT campus, 1500 Stony Brook Rd, a 8 km fiber distance from the ECC building in the main SBU campus. It will be equipped with telecom single photon counters for polarization characterization.
  • Finally, Node B will be located in the MANLAN fiber exchange point, 32 Avenue of the Americas in New York City, a 60 km fiber distance from the Garden City substation. It will be equipped with telecom single photon counters for polarization characterization.
  • All nodes and substations will be equipped with servers, Stratum-1 servers, light-digital transducers and fast FPGA processors, to perform the tasks described in Thrust V.

Additional deliverable in Year 2: A coordinated two-layer network using optical control signals managing the delivery of entanglement in addition to the quantum repeater architecture.

Test bed of a two-layer classical/quantum network targeted to optically control entanglement swapping.} The first entangled source + controlling hardware is located in the SBU ECC building (Substation 1). The second entangled source + controlling hardware are located in the Garden City fiber exchange point (Substation 3). A Bell state measurement substation + controlling hardware is located in the SDCC in the ITD BNL building (Substation 2). Distant nodes A and B are located in the CEWIT campus (SBU) and the MANLAN fiber exchange point, in New York City, respectively.

2. Towards cascading quantum repeater hops.

Recent theoretical results have shown that quantum repeater hops can be chained to extend entanglement distribution over arbitrarily long distances. After the demonstration of a fully-operational quantum repeater hop working with quantum memory buffers and telecom entangled photons, we will use the additional resources of this proposal to establish the infrastructure needed to cascade two quantum repeater hops. This second extension of our infrastructure will use the optically controlled entanglement swapping network described in Thrust VI plus the following additions (many covered in the original proposal work):

  • A new Substation (marked as substation 2 in Fig. 13) located at the Quantum Technology Laboratory in SBU, equipped with two telecom compatible quantum memory buffers and a telecom Bell state measurement setup, using nano-wire single photon counters for minimal dark counts of less that one per second.
  • Addition of two quantum memory buffers to the Bell state measurement substation in BNL.
  • Addition of a portable memory-compatible telecom entanglement source in the Quantum Information Science and Technology laboratory in the Instrumentation Division (IO) building at BNL with an estimated entangled pair production ratio of 105 ebits/sec.
  • Addition of quantum memory buffers to the distant nodes A and B.

Additional deliverable in Year 3: Addition of the necessary infrastructure and start of the deployment of extra-hardware for a large network with cascaded quantum repeater hops.

Proposed realization of cascaded quantum repeater hops. Inset: Schematic diagram of a chain of quantum repeater hops. Diagram of a proposed network of chained quantum repeaters to be built on Long Island, with the elements highlighted: three entangled-pair sources (“∞” symbol), located in the ECC SBU buidling (substation 1), ITD Building in BNL (substation 3) and the Garden city fiber exchange point (substation 5), two memory-assisted Bell state measurements (“atom” symbol), located in the SBU QIT laboratory (substation 2) and the BNL Instrumentation QIST laboratory (substation 4), and remote nodes A and B, also equipped with quantum memory buffers locates in the in SBU CEWIT building and the New York City MANLAN exchange point.