Saikat Guha | Raytheon BBN Technologies (original) (raw)
Papers by Saikat Guha
2012 IEEE International Symposium on Information Theory Proceedings
In the low-energy high-energy-efficiency regime of classical optical communications-relevant to d... more In the low-energy high-energy-efficiency regime of classical optical communications-relevant to deep-space optical channels-there is a big gap between reliable communication rates achievable via conventional optical receivers and the ultimate (Holevo) capacity. Achieving the Holevo capacity requires not only optimal codes but also receivers that make collective measurements on long (modulated) codeword waveforms, and it is impossible to implement these collective measurements via symbol-by-symbol detection along with classical postprocessing [1], [2]. Here, we apply our recent results on the classicalquantum polar code [3]-the first near-explicit, linear, symmetric-Holevo-rate achieving code-to the lossy optical channel, and we show that it almost closes the entire gap to the Holevo capacity in the low photon number regime. In contrast, Arikan's original polar codes, applied to the DMC induced by the physical optical channel paired with any conceivable structured optical receiver (including optical homodyne, heterodyne, or directdetection) fails to achieve the ultimate Holevo limit to channel capacity. However, our polar code construction (which uses the quantum fidelity as a channel parameter rather than the classical Bhattacharyya quantity to choose the "good channels" in the polar-code construction), paired with a quantum successivecancellation receiver-which involves a sequence of collective non-destructive binary projective measurements on the joint quantum state of the received codeword waveform-can attain the Holevo limit, and can hence in principle achieve higher rates than Arikan's polar code and decoder directly applied to the optical channel. However, even a theoretical recipe for construction of an optical realization of the quantum successivecancellation receiver remains an open question.
We investigate the spontaneous emission of a two-level atom in one dimensional photonic crystals ... more We investigate the spontaneous emission of a two-level atom in one dimensional photonic crystals composed of left-hand material (LHM) and right-hand material (RHM). A complete set of mode functions is constructed for the quantization of the radiation field. It is found that the mode functions for the frequency with in the band gap decreases exponentially from the surface to the interior of the photonic crystal which results in a much weaker field than the vacuum in the free space.
Coherent-state inputs are conjectured to minimize the von Neumann entropies at the outputs of two... more Coherent-state inputs are conjectured to minimize the von Neumann entropies at the outputs of two Bosonic channels with thermal noise. Evidence in support of this conjecture is provided, including the fact that coherent-state inputs minimize the integer-order Rényi entropy and the Wehrl entropy at the outputs of these channels. A stronger conjecture—that output states resulting from coherent-state inputs majorize the output states from other inputs—is also discussed.© 2004 American Institute of Physics
Abstract—Existence and properties of percolating paths through dense random networks have been, i... more Abstract—Existence and properties of percolating paths through dense random networks have been, in recent years, shown to be useful in uncovering a variety of new results and insights into wireless networking and communications. Examples include several results on wireless network capacity, secure communications in the presence of multiple eavesdroppers, latencyoptimal energy-efficient duty cycling, and scaling laws for multicast throughput in extended wireless networks.
Abstract Rate-(n-2)/n unrestricted and CSS-type quantum convolutional codes with up to 4096 state... more Abstract Rate-(n-2)/n unrestricted and CSS-type quantum convolutional codes with up to 4096 states and minimum distances up to 10 are constructed as stabilizer codes from classical self-orthogonal rate-1/n F 4-linear and binary linear convolutional codes, respectively. These codes generally have higher rate and less decoding complexity than comparable quantum block codes or previous quantum convolutional codes.
Abstract Simple rate-1/3 single-error-correcting unrestricted and CSS-type quantum convolutional ... more Abstract Simple rate-1/3 single-error-correcting unrestricted and CSS-type quantum convolutional codes are constructed from classical self-orthogonal F 4-linear and F 2-linear convolutional codes, respectively. These quantum convolutional codes have higher rate than comparable quantum block codes or previous quantum convolutional codes, and are simple to decode.
Abstract Holevo, Schumacher, and Westmorelands coding theorem guarantees the existence of codes t... more Abstract Holevo, Schumacher, and Westmorelands coding theorem guarantees the existence of codes that are capacityachieving for the task of sending classical data over a channel with classical inputs and quantum outputs. Although they demonstrated the existence of such codes, their proof does not provide an explicit construction of codes for this task. The aim of the present paper is to fill this gap by constructing nearexplicit polar codes that are capacity-achieving.
The quantum states of two laser pulses—coherent states—are never mutually orthogonal, making perf... more The quantum states of two laser pulses—coherent states—are never mutually orthogonal, making perfect discrimination impossible. Even so, coherent states can achieve the ultimate quantum limit for capacity of a classical channel, the Holevo capacity. Attaining this requires the receiver to make joint-detection measurements on long codeword blocks, optical implementations of which remain unknown.
Abstract An optical transmitter that uses entangled light generated by spontaneous parametric dow... more Abstract An optical transmitter that uses entangled light generated by spontaneous parametric downconversion (SPDC), in conjunction with an optimal quantum-optical receiver (whose implementation is not yet known) is in principle capable of obtaining up to a 6 dB gain in the error-probability exponent over the optimum-reception un-entangled coherent-state lidar to detect the presence of a far-away target subject to entanglement-breaking loss and noise in the free-space link.
Abstract We show that when coherent-state encoding is employed in conjunction with coherent detec... more Abstract We show that when coherent-state encoding is employed in conjunction with coherent detection, the Bosonic broadcast channel is equivalent to a classical degraded Gaussian broadcast channel whose capacity region is dual to that of the classical Gaussian multiple-access channel. We further show that if a minimum output-entropy conjecture holds true, then the ultimate classical information capacity of the Bosonic broadcast channel can be achieved by a coherent-state encoding.
Abstract In the low-energy high-energy-efficiency regime of classical optical communications—rele... more Abstract In the low-energy high-energy-efficiency regime of classical optical communications—relevant to deep-space optical channels—there is a big gap between reliable communication rates achievable via conventional optical receivers and the ultimate (Holevo) capacity.
A prominent landmark in the extension of Shannon information theory to the quantum domain is the ... more A prominent landmark in the extension of Shannon information theory to the quantum domain is the realization that any particular physical system can store only a finite amount of information. As a consequence, the quantity of information that can be exchanged in any communication process is limited by the available physical resources. Two of the main results in this regard are the Holevo bound1 and the Holevo-Schumacher-Westmoreland (HSW) theorem.
Abstract We consider the problem of demodulating M-ary optical PPM (pulse-position modulation) wa... more Abstract We consider the problem of demodulating M-ary optical PPM (pulse-position modulation) waveforms, and propose a structured receiver whose mean probability of symbol error is smaller than all known receivers, and approaches the quantum limit. The receiver uses photodetection coupled with optimized phase-coherent optical feedback control and a phase-sensitive parametric amplifier.
Abstract: We analyze the practical performance of quantum polar codes, by computing rigorous boun... more Abstract: We analyze the practical performance of quantum polar codes, by computing rigorous bounds on block error probability and by numerically simulating them. We evaluate our bounds for quantum erasure channels with coding block lengths between 2^ 10 and 2^ 20, and we report the results of simulations for quantum erasure channels, quantum depolarizing channels, and" BB84" channels with coding block lengths up to N= 1024.
Abstract While scheduling the nodes in a wireless network to sleep periodically can save energy, ... more Abstract While scheduling the nodes in a wireless network to sleep periodically can save energy, it also incurs higher latency and lower throughput. We consider the problem of designing optimal sleep schedules in wireless networks, and show that finding sleep schedules that can minimize the latency over a given subset of source-destination pairs is NP-hard.
Abstract: We show that nature imposes no fundamental upper limit to the number of information bit... more Abstract: We show that nature imposes no fundamental upper limit to the number of information bits per expended photon that can, in principle, be read reliably when classical data is encoded in a medium that can only passively modulate the amplitude and phase of the probe light.
The capacity C for transmitting classical information is investigated for Bosonic channels with i... more The capacity C for transmitting classical information is investigated for Bosonic channels with isotropic Gaussian noise. For the pure-loss channel—in which signal photons may be lost in propagation—the exact value of C is derived. The Holevo information of this channel is shown to be additive, and a “classical” encoding procedure employing coherent states is shown to achieve capacity.
Feature Issue on Optical Wireless Communications (OWC) The ultimate classical information capacit... more Feature Issue on Optical Wireless Communications (OWC) The ultimate classical information capacity of multiple-spatial-mode, wideband optical communications in vacuum between soft-aperture transmit and receive pupils is considered. The ultimate capacity is shown to be achieved by coherent-state encoding and joint measurements over entire code words.
The first examples of Bohmian trajectories for photons have been worked out for simple situations... more The first examples of Bohmian trajectories for photons have been worked out for simple situations, using the Kemmer-Duffin-Harish-Chandra formalism.
Abstract—Opportunistic forwarding is a simple scheme for packet routing in delay tolerant network... more Abstract—Opportunistic forwarding is a simple scheme for packet routing in delay tolerant networks such as duty cycling sensor networks in which reducing energy consumption is a principal goal. While it is simple and can be analytically characterized, it suffers from a high end-to-end latency.
2012 IEEE International Symposium on Information Theory Proceedings
In the low-energy high-energy-efficiency regime of classical optical communications-relevant to d... more In the low-energy high-energy-efficiency regime of classical optical communications-relevant to deep-space optical channels-there is a big gap between reliable communication rates achievable via conventional optical receivers and the ultimate (Holevo) capacity. Achieving the Holevo capacity requires not only optimal codes but also receivers that make collective measurements on long (modulated) codeword waveforms, and it is impossible to implement these collective measurements via symbol-by-symbol detection along with classical postprocessing [1], [2]. Here, we apply our recent results on the classicalquantum polar code [3]-the first near-explicit, linear, symmetric-Holevo-rate achieving code-to the lossy optical channel, and we show that it almost closes the entire gap to the Holevo capacity in the low photon number regime. In contrast, Arikan's original polar codes, applied to the DMC induced by the physical optical channel paired with any conceivable structured optical receiver (including optical homodyne, heterodyne, or directdetection) fails to achieve the ultimate Holevo limit to channel capacity. However, our polar code construction (which uses the quantum fidelity as a channel parameter rather than the classical Bhattacharyya quantity to choose the "good channels" in the polar-code construction), paired with a quantum successivecancellation receiver-which involves a sequence of collective non-destructive binary projective measurements on the joint quantum state of the received codeword waveform-can attain the Holevo limit, and can hence in principle achieve higher rates than Arikan's polar code and decoder directly applied to the optical channel. However, even a theoretical recipe for construction of an optical realization of the quantum successivecancellation receiver remains an open question.
We investigate the spontaneous emission of a two-level atom in one dimensional photonic crystals ... more We investigate the spontaneous emission of a two-level atom in one dimensional photonic crystals composed of left-hand material (LHM) and right-hand material (RHM). A complete set of mode functions is constructed for the quantization of the radiation field. It is found that the mode functions for the frequency with in the band gap decreases exponentially from the surface to the interior of the photonic crystal which results in a much weaker field than the vacuum in the free space.
Coherent-state inputs are conjectured to minimize the von Neumann entropies at the outputs of two... more Coherent-state inputs are conjectured to minimize the von Neumann entropies at the outputs of two Bosonic channels with thermal noise. Evidence in support of this conjecture is provided, including the fact that coherent-state inputs minimize the integer-order Rényi entropy and the Wehrl entropy at the outputs of these channels. A stronger conjecture—that output states resulting from coherent-state inputs majorize the output states from other inputs—is also discussed.© 2004 American Institute of Physics
Abstract—Existence and properties of percolating paths through dense random networks have been, i... more Abstract—Existence and properties of percolating paths through dense random networks have been, in recent years, shown to be useful in uncovering a variety of new results and insights into wireless networking and communications. Examples include several results on wireless network capacity, secure communications in the presence of multiple eavesdroppers, latencyoptimal energy-efficient duty cycling, and scaling laws for multicast throughput in extended wireless networks.
Abstract Rate-(n-2)/n unrestricted and CSS-type quantum convolutional codes with up to 4096 state... more Abstract Rate-(n-2)/n unrestricted and CSS-type quantum convolutional codes with up to 4096 states and minimum distances up to 10 are constructed as stabilizer codes from classical self-orthogonal rate-1/n F 4-linear and binary linear convolutional codes, respectively. These codes generally have higher rate and less decoding complexity than comparable quantum block codes or previous quantum convolutional codes.
Abstract Simple rate-1/3 single-error-correcting unrestricted and CSS-type quantum convolutional ... more Abstract Simple rate-1/3 single-error-correcting unrestricted and CSS-type quantum convolutional codes are constructed from classical self-orthogonal F 4-linear and F 2-linear convolutional codes, respectively. These quantum convolutional codes have higher rate than comparable quantum block codes or previous quantum convolutional codes, and are simple to decode.
Abstract Holevo, Schumacher, and Westmorelands coding theorem guarantees the existence of codes t... more Abstract Holevo, Schumacher, and Westmorelands coding theorem guarantees the existence of codes that are capacityachieving for the task of sending classical data over a channel with classical inputs and quantum outputs. Although they demonstrated the existence of such codes, their proof does not provide an explicit construction of codes for this task. The aim of the present paper is to fill this gap by constructing nearexplicit polar codes that are capacity-achieving.
The quantum states of two laser pulses—coherent states—are never mutually orthogonal, making perf... more The quantum states of two laser pulses—coherent states—are never mutually orthogonal, making perfect discrimination impossible. Even so, coherent states can achieve the ultimate quantum limit for capacity of a classical channel, the Holevo capacity. Attaining this requires the receiver to make joint-detection measurements on long codeword blocks, optical implementations of which remain unknown.
Abstract An optical transmitter that uses entangled light generated by spontaneous parametric dow... more Abstract An optical transmitter that uses entangled light generated by spontaneous parametric downconversion (SPDC), in conjunction with an optimal quantum-optical receiver (whose implementation is not yet known) is in principle capable of obtaining up to a 6 dB gain in the error-probability exponent over the optimum-reception un-entangled coherent-state lidar to detect the presence of a far-away target subject to entanglement-breaking loss and noise in the free-space link.
Abstract We show that when coherent-state encoding is employed in conjunction with coherent detec... more Abstract We show that when coherent-state encoding is employed in conjunction with coherent detection, the Bosonic broadcast channel is equivalent to a classical degraded Gaussian broadcast channel whose capacity region is dual to that of the classical Gaussian multiple-access channel. We further show that if a minimum output-entropy conjecture holds true, then the ultimate classical information capacity of the Bosonic broadcast channel can be achieved by a coherent-state encoding.
Abstract In the low-energy high-energy-efficiency regime of classical optical communications—rele... more Abstract In the low-energy high-energy-efficiency regime of classical optical communications—relevant to deep-space optical channels—there is a big gap between reliable communication rates achievable via conventional optical receivers and the ultimate (Holevo) capacity.
A prominent landmark in the extension of Shannon information theory to the quantum domain is the ... more A prominent landmark in the extension of Shannon information theory to the quantum domain is the realization that any particular physical system can store only a finite amount of information. As a consequence, the quantity of information that can be exchanged in any communication process is limited by the available physical resources. Two of the main results in this regard are the Holevo bound1 and the Holevo-Schumacher-Westmoreland (HSW) theorem.
Abstract We consider the problem of demodulating M-ary optical PPM (pulse-position modulation) wa... more Abstract We consider the problem of demodulating M-ary optical PPM (pulse-position modulation) waveforms, and propose a structured receiver whose mean probability of symbol error is smaller than all known receivers, and approaches the quantum limit. The receiver uses photodetection coupled with optimized phase-coherent optical feedback control and a phase-sensitive parametric amplifier.
Abstract: We analyze the practical performance of quantum polar codes, by computing rigorous boun... more Abstract: We analyze the practical performance of quantum polar codes, by computing rigorous bounds on block error probability and by numerically simulating them. We evaluate our bounds for quantum erasure channels with coding block lengths between 2^ 10 and 2^ 20, and we report the results of simulations for quantum erasure channels, quantum depolarizing channels, and" BB84" channels with coding block lengths up to N= 1024.
Abstract While scheduling the nodes in a wireless network to sleep periodically can save energy, ... more Abstract While scheduling the nodes in a wireless network to sleep periodically can save energy, it also incurs higher latency and lower throughput. We consider the problem of designing optimal sleep schedules in wireless networks, and show that finding sleep schedules that can minimize the latency over a given subset of source-destination pairs is NP-hard.
Abstract: We show that nature imposes no fundamental upper limit to the number of information bit... more Abstract: We show that nature imposes no fundamental upper limit to the number of information bits per expended photon that can, in principle, be read reliably when classical data is encoded in a medium that can only passively modulate the amplitude and phase of the probe light.
The capacity C for transmitting classical information is investigated for Bosonic channels with i... more The capacity C for transmitting classical information is investigated for Bosonic channels with isotropic Gaussian noise. For the pure-loss channel—in which signal photons may be lost in propagation—the exact value of C is derived. The Holevo information of this channel is shown to be additive, and a “classical” encoding procedure employing coherent states is shown to achieve capacity.
Feature Issue on Optical Wireless Communications (OWC) The ultimate classical information capacit... more Feature Issue on Optical Wireless Communications (OWC) The ultimate classical information capacity of multiple-spatial-mode, wideband optical communications in vacuum between soft-aperture transmit and receive pupils is considered. The ultimate capacity is shown to be achieved by coherent-state encoding and joint measurements over entire code words.
The first examples of Bohmian trajectories for photons have been worked out for simple situations... more The first examples of Bohmian trajectories for photons have been worked out for simple situations, using the Kemmer-Duffin-Harish-Chandra formalism.
Abstract—Opportunistic forwarding is a simple scheme for packet routing in delay tolerant network... more Abstract—Opportunistic forwarding is a simple scheme for packet routing in delay tolerant networks such as duty cycling sensor networks in which reducing energy consumption is a principal goal. While it is simple and can be analytically characterized, it suffers from a high end-to-end latency.