Data Ingress and Egress for Cryogenic Systems

The Intelligence Advanced Research Projects Activity seeks information on the availability and development of technology and techniques for high data rate transmission of digital signals between a room temperature system and a cryogenic system at a temperature of approximately 4 kelvins. This request for information is issued solely for information gathering and planning purposes; this RFI does not constitute a formal solicitation for proposals. The following sections of this RFI define the overall scope of the technical domain of interest, along with instructions for the preparation and submission of responses.

Background & Scope

The President’s National Strategic Computing Initiative assigns IARPA the role of foundational research for future computing paradigms offering an alternative to standard semiconductor computing technology. Candidate paradigms include various methods of computing at cryogenic temperatures (e.g., digital, analog, reversible, neuromorphic, or quantum). Specific examples include digital computation as being developed by IARPA’s C3 program, software defined radio, and quantum annealing processors. Cryogenic computing may use digital or analog electrical signals at cryogenic temperatures, but must communicate with networks operating at room temperature. A key consideration for the system connecting the two environments is that the cost in terms of electrical power and of transmitted thermal power be on par with that of the rest of the system. This implies the use of optical fiber technology for large scale computing systems.

Capabilities of interest include:

Data Out:

  1. For analog signals, the transmission of one or more analog signals from cryogenic circuits at ~ 4 K to analog-to-digital converters
  2. Analog-to-digital conversion of the signals
  3. Signals already in digital format to be used directly
  4. Multiplexing multiple digital channels into a single digital stream
  5. Transmission to the room temperature environment using optical fiber

Data In:

  1. Transmission of a single digital stream carrying one or more digital signals over optical fiber from room temperature into the cryogenic environment
  2. Demultiplexing multiple channels from the single digital stream
  3. Interfacing with cryogenic digital circuits

Desired information for these capabilities includes the current state-of-the art, improvements needed, and effort required to improve the state-of-the-art. Additional considerations and details:

  • ADC capabilities of interest include: sensitivity, data rate, operating temperature range, signal-to-noise ratio, and dynamic range. Anticipated analog capabilities include 10 channels, each operating in the HF/VHF bands with a 60-80 dB S/N ratio, to be multiplexed into a single digital stream.
  • Digital data at ~4 K may be encoded using single flux quantum pulses in superconducting circuits. The SFQ pulses are typically a few picoseconds wide and about one millivolts high on 10 to 50 ohm superconducting lines. Consider digital data rates beginning at 25 Gb/s up to aggregated rates of 80 Pb/s (8x10^16 bits per second).
  • Some cryogenic computing systems may not require processing analog signals. Such systems would only require egress of digital electrical data from ~4 K to room temperature, and ingress of digital data from room temperature to ~4 K.
  • Energy efficiency is very important for components operating at cryogenic temperatures.

For an evaluation of the current state of the art of fiber optic technology for use in High Performance Computing, see the website:

IARPA anticipates that the following technologies may play a role in this advanced transmission system. The following is not intended to be prescriptive or restrictive.

  • For analog data at low temperature, the system may require superconducting circuitry, including analog to digital convertors.
  • The optimized system may include multiple technologies along the path, located at various temperature stages.
  • The system may include various transmission technologies to carry data between different temperature stages.
  • For lower data rates, the optimal system may not require optics within the cryogenic environment.
  • Low loss optical components, including DWDM multiplexers and demultiplexers may be beneficial. Low optical loss and low electrical drive power modulators may be useful for the final uplink to room temperature.
  • The conversion between optical and electrical data or between analog electrical and digital electrical may take place at intermediate temperatures.

Preferred responses to this RFI will include information on systems capable of performing at least one of the following two processes:

  1. Transmit analog electrical data at ~4 K to digital optical data at room temperature, and digital optical data at room temperature to digital SFQ data at ~4 K.
  2. Transmit digital SFQ data at ~4 K to digital optical data at room temperature, and digital optical data at room temperature to digital SFQ data at ~4 K.

Responses to this RFI may include more than one approach for optimal data transmission at different data rates, systems that are totally digital, or those that include analog data. Responses should include an evaluation of the energy efficiency for each component of the data transmission systems as well as an overall efficiency for each approach. IARPA will accept partial approaches. Also useful would be a discussion of the problems expected to be encountered — and possible solutions — as the system is scaled to petascale or exascale data rates.

Preparation Instructions to Respondents

IARPA requests that submittals briefly and clearly describe the potential approaches and concepts, outline critical technical issues and obstacles, describe how the approaches may address those issues and obstacles, and comment on the expected performance and robustness of the proposed approaches. If appropriate, respondents may also choose to provide a non-proprietary rough order of magnitude regarding what such approaches might require in terms of funding and other resources for one or more years. This announcement contains all of the information required to submit a response. No additional forms, kits, or other materials are needed.

IARPA appreciates responses from all capable and qualified sources from within and outside of the US. Because IARPA is interested in an integrated approach, responses from teams with complementary areas of expertise are encouraged.

Responses have the following formatting requirements:

  1. A one-page cover sheet that identifies the response title, organization(s), respondent's technical and administrative points of contact - including names, addresses, phone and fax numbers, and email addresses of all co-authors, and clearly indicating its association with IARPA-RFI-16-04;
  2. A substantive, focused, one-half page executive summary;
  3. A technical section of no more than ten pages;
  4. A list of citations (any significant claims or reports of success must be accompanied by citations);
  5. Optionally, a single overview briefing chart graphically depicting the key ideas.

Submission Instructions to Respondants

Responses to this RFI are due no later than 4:00 p.m., Local Time, College Park, MD on Tuesday, March 1, 2016. All submissions must be electronically submitted to as a PDF document. Inquiries to this RFI must be submitted to Do not send questions with proprietary content. No telephone inquiries will be accepted.

Disclaimers and Important Notes

This is an RFI issued solely for information and planning purposes and does not constitute a solicitation. Respondents are advised that IARPA is under no obligation to acknowledge receipt of the information received, or provide feedback to respondents with respect to any information submitted under this RFI. Responses to this notice are not offers and cannot be accepted by the Government to form a binding contract. Respondents are solely responsible for all expenses associated with responding to this RFI. IARPA will not provide reimbursement for costs incurred in responding to this RFI. It is the respondent's responsibility to ensure that the submitted material has been approved for public release by the information owner. The Government does not intend to award a contract on the basis of this RFI or to otherwise pay for the information solicited, nor is the Government obligated to issue a solicitation based on responses received. Neither proprietary nor classified concepts or information should be included in the submittal. Input on technical aspects of the responses may be solicited by IARPA from non-Government consultants/experts who are bound by appropriate non-disclosure requirements.

Contact Information:


Posted Date: January 28, 2016
Responses Due: March 1, 2016