Attachment 4 Questions and Answers.docx

Questions and Answers USAFA: Quantum Demonstration/Experiment System The Government's primary objective is a laboratory system capable of demonstrating polarization entanglement, heralded photon detection, Bell-state measurements, and entanglement swapping suitable for upper-division undergraduate instruction and faculty research.

· Q: Are you interested in a complete system with Detectors, Time-Taggers and Polarization entangled source?

· A: A complete integrated system is preferred. The Government desires a turnkey system consisting of polarization-entangled photon source(s), single-photon detectors, timing/correlation electronics, software, and all required interfaces. Components shall be demonstrated by the vendor to operate together as a complete entanglement characterization and entanglement-swapping platform

· Q: You do not specify the type of detectors. Are the end users wanting Super Conducting Nanowire detectors with very high PDE, or Silicon and InGaAs SPAD detectors?

· A: The Government does not require specific detector technology. Acceptable solutions may include SNSPD, silicon SPAD, or InGaAs SPAD detectors. Detectors shall support operation in the near-infrared range with a preferred operating range including approximately 800-1000 nm and, if practical, extension into the telecom band near 1550 nm. Timing jitter should be suitable for coincidence and heralded-photon measurements, preferably less than 100 ps.

· Q: Attachment 1 states that the components shall support the characterization of polarization-entangled photon pairs via SPDC. Could the Government confirm whether the entangled-photon source or sources, together with the associated free-space or fiber optics, polarizing optics, waveplates, and mounting hardware, are within the scope of this requirement, or whether USAFA will provide existing source and optical hardware for the delivered system to interface with?

· A: USAFA possesses beta-BBO crystals, quartz compensators, waveplates, optical mounts, and related optics. Vendors may propose either a complete source subsystem or a system that interfaces with existing laboratory components. Compatibility with user-supplied SPDC hardware should be described.

· Q: Entanglement swapping, as listed in Attachment 1, typically requires two independent photon-pair sources. If sources are within scope, could the Government confirm the number of sources expected?

· A: The intended application is entanglement swapping and related quantum networking demonstrations. The Government anticipates operation with two independent entangled-photon sources. Vendors may propose integrated or modular solutions.

· Q: Does USAFA currently operate single photon detectors, timing electronics, or an SPDC source at the Physics Department or the Laser and Optics Research Center that the delivered system must interface with or complement? If so, could the Government identify the make and model so that compatibility can be confirmed?

· A: USAFA currently has a Picoquant MultiHarp-150/160 and two Excelitas single-photon detectors. Compatibility with existing equipment is desirable but not mandatory unless specifically identified by the vendor.

· Q: Should a computer or workstation for data acquisition be included in the quoted system, or will the Government provide one?

· A: The Government will provide a laptop/workstation. Vendor-supplied software shall operate on the provided computer and support data acquisition and coincidence analysis.

· Q: Could the Government identify the intended operating wavelength or wavelength range for the single photon detectors? Specifically, is the near infrared requirement intended to cover the silicon detection range up to approximately 1000 nm, or does it extend into the telecom band around 1550 nm?

· A: The primary operating wavelength range is expected to be approximately 800-1000 nm to support SPDC experiments using existing laboratory optics and nonlinear crystals. Solutions capable of operation near 1310 nm and/or 1550 nm for future quantum networking and telecom-band experiments are highly desirable.

· Q: Attachment 1 requires multiple single photon detectors. Could the Government specify a required or preferred minimum quantity? For reference, four detectors support a minimum four-photon entanglement swapping configuration, while eight detectors allow full polarization analysis at both the Bell-state measurement and the outer photon arms.

· A: Four detectors is the minimum acceptable quantity. Additional detectors that support complete Bell-state measurements, polarization analysis, and future entanglement-swapping experiments are desirable.

· Q: Are free-space coupled or fiber coupled detectors preferred, or is acceptable?

· A: Either free-space or fiber-coupled detectors are acceptable. Fiber-coupled detectors are preferred due to ease of alignment and integration into quantum networking experiments.

· Q: Does the Government have minimum numeric thresholds for detection efficiency, dark count rate, or timing jitter, or will vendor-specified performance be evaluated comparatively against the qualitative characteristics in Attachment 1?

· A: The Government has not established mandatory thresholds. Preferred performance characteristics are:

· High photon detection efficiency

· Low dark count rate 250cps

· Timing jitter preferably below 100 ps

· Performance suitable for heralded-photon coincidence measurements and entanglement characterization Vendors should provide specifications and measured performance data.

· Q: Does the Government have a required minimum number of input channels for the time tagging or TCSPC electronics, and a required maximum coincidence fold order, for example four-fold or higher?

· A: A minimum of four synchronized timing channels is required. Systems supporting expansion to additional channels for multi-photon and entanglement-swapping experiments are preferred.

· Q: Attachment 1 requires high sustained count rates without significant dead time. Could the Government indicate a target sustained count rate, if one has been established?

· A: No formal threshold has been established. The system should support sustained coincidence measurements for instructional laboratory and research applications without significant performance degradation due to dead time or count-rate limitations.

· Q: For instructional laboratory use, does the Government require software licensing for multiple simultaneous users or installations? Are on-site or remote installation, commissioning, and training expected as part of the delivered system?

· A: On-site installation and commissioning are desired. Formal training is not required but would be beneficial. Vendor technical support and troubleshooting assistance during system setup and acceptance are highly desirable. Software licensing for a single laboratory computer is sufficient.