Integrated scalable quantum receiver for energy efficient data exchange and telecommunication

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Nontechnical descriptionThis project describes a new way to minimize the energy and bandwidth required to transmit a bit of information. It achieves this by replacing a classical receiver with a quantum receiver. An encoding scheme based on coherent frequency shift keying, together with a quantum receiver, is used to preserve the advantage of quantum measurement even when a large number of parameters (frequency de-tunings, amplitudes and phases) are used to encode the transmitted signal, leading to higher transmission rates. A scheme is proposed to build an integrated transmitter and receiver to demonstrate a quantum-enhanced scalable data exchange link operating at 100 Mb/s at a wavelength of 1.5 m. It will be the first ever quantum receiver that operates at telecom wavelengths. A more efficient use of bandwidth in addition to energy efficiency will be demonstrated for the first time by using a non-classical receiver. The combination of low loss and high efficiency optical circuitry together with coherent frequency shift keying encoding will achieve the absolute quantum advantage of a quantum receiver. Ultimately, this approach will lead to a more energy efficient internet and less power dissipation in data banks and improved deep space communication.Technical descriptionThe first quantum receiver whose quantum advantage is scalable is proposed. It will be the first-ever integrated quantum receiver that operates at telecom wavelengths. It will allow both energy efficiency beyond the standard quantum limit and bandwidth optimization. The combination of low loss and high efficiency optical circuitry together with coherent frequency shift keying (CSFK) encoding will achieve the absolute quantum advantage of a quantum receiver. CSFK is a family of M-ary coherent communication protocols that arises from the use of M different coherent states that differs by frequency and/or phase. The advantage of all quantum receivers that have been demonstrated to date quickly disappears with large alphabet sizes. An encoding scheme has been invented by the principal/co-principal team to get around this problem. This scheme preserves the advantage of quantum measurement even as the alphabet size is scaled to large size, thus enabling high-speed quantum-enhanced communication. A quantum-enhanced receiver can exceed the sensitivity limit of classical receivers and push the sensitivity toward a much lower fundamental limit known as the Helstrom bound. At this limit, the classical Shannon theory does not accurately describe the relation between signal and noise, bandwidth and data rate. An integrated transmitter and receiver will be built on a silicon-on-insulator (SOI) platform to demonstrate a quantum-enhanced, scalable data exchange a wavelength of 1.5 m capable of operating at 100 Mb/s to establish its quantum supremacy in energy and bandwidth use. A modulator based on carrier depletion in a reversed-biased pn diode structure will be implemented. The modulator will consist of two sub Mach-Zehnder (MZ) structures embedded in a main MZ structure. The integrated receiver will be attached to a high quantum efficiency superconducting nanowire detector. Two communication protocols, one that optimizes the energy per bit and the other that optimizes the bandwidth usage beyond what is classically achievable, will be demonstrated. The ultimate goal of this work, beyond the scope of this proposal, is to establish practically achievable and absolute limits for resource-efficient communications. Although the envisaged receiver design beats classical limits of detection in both energy per bit and bandwidth, further improvements are possible. The channel has the potential to be used to communicate with extremely faint classical states of light at the receivers input and thus violate the classical heterodyne Shannon power efficiency limit of 0.69 photons/bit.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.