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Superradiance-enhanced quantum state transfer through time reversal of an optical channel

Michael Hush, C. D. Bentley, Rose L. Ahlefeldt, M. R. James, Matthew J. Sellars, Valery Ugrinovskii

Published Mar 17, 2016• 0 citations
OpenAlex

Abstract

Rare earth ions have exceptionally long coherence times, making them an excellent candidate for quantum information processing. A key part of this processing is quantum state transfer. We demonstrate that high fidelity quantum state transfer between two ensembles of rare earth ions can be achieved by time reversing the connecting optical quantum channel, and suggest using a gradient echo memory to perform this time reversal. We demonstrate that the superradiant coupling between the ensemble of ions and an intermediate cavity coupled to the optical channel can lead to higher transfer fidelities than would otherwise be possible with an individual ion. We suggest increasing the size of the ensemble can overcome unwanted loss and decoherence processes that reduce the transfer fidelity.

Related papers

Quantum state transfer through time reversal of an optical channel

Michael Hush, C. D. Bentley, Rose L. Ahlefeldt +3 more

Rare-earth ions have exceptionally long coherence times, making them an excellent candidate for quantum information processing. A key part of this processing is quantum state transfer. We show that perfect state transfer can be achieved by time reversing the intermediate quantum channel, and suggest using a gradient echo memory (GEM) to perform this time reversal. We propose an experiment with rare-earth ions to verify these predictions, where an emitter and receiver crystal are connected with an optical channel passed through a GEM. We investigate the effect experimental imperfections and collective dynamics have on the state transfer process. We demonstrate that super-radiant effects can enhance coupling into the optical channel and improve the transfer fidelity. We lastly discuss how our results apply to state transfer of entangled states.

arXiv:1603.05327•Physical Review A•Dec 5, 2016•4 citations

Broadband photonic quantum interface based on a cavity-protected rare-earth ensemble

Tian Zhong, Jonathan M. Kindem, Jake Rochman +1 more

Rare-earth ions doped in crystals are renowned for their excellent coherence properties and large inhomogeneous broadening, which make them ideal for quantum interfaces with broadband photons. These properties have made them one of the leading technologies in quantum optical memories and a promising candidate for optical-to-microwave conversion. To take advantage of the full bandwidth of the rare-earth ensemble, one must overcome the decoherence of a broadband collective excitation due to inhomogeneous broadening. To this end, techniques based on controllable rephasing, such as atomic frequency comb (AFC) or controlled reversible inhomogeneous broadening (CRIB) memories, have been developed with great success. Recently, an alternative method was proposed to suppress the decoherence of an inhomogeneous ensemble via strong coupling to a cavity, a phenomenon called cavity protection. This technique has been demonstrated in the microwave domain with an NV spin ensemble, but has not been demonstrated in the optical domain. Here, we demonstrate cavity protection in the optical domain at the single photon level using an ensemble of rare earths ions coupled to a nanophotonic resonator. The reduction in decoherence due to the cavity-protection effect enables transfer of ultrafast (~50 GHz) frequency qubits into the collective ion excitation and retrieval with 98.7% fidelity. Building on these results to transfer these excitations to long-lived spin states would enable broadband, on-demand quantum memories. Furthermore, this works compliments the work done coupling rare-earths to superconducting resonators in the microwave regime with potential for applications in optical-to-microwave transducers.

•Jun 2, 2017•0 citations

Quantum nano-photonic devices based on rare-earth ions (Conference Presentation)

Andrei Faraon

I present quantum nano-photonic devices based on nanophotonic resonators coupled to rare-earth-ions in crystals. The rare-earth ions exhibit long coherence times on optical transitions, which makes them suitable for optical quantum memories. We demonstrate a high-fidelity nanophotonic quantum memory based on a mesoscopic rare-earth ensemble coupled to a photonic crystal cavity. The nanocavity enables >95% spin polarization for efficient initialization of the atomic frequency comb memory, and time-bin-selective readout via enhanced optical Stark shift of the comb frequencies. Besides ensemble memories, single rare-earth-ions coupled to nano-resonators can be used as single optically addressable quantum bits where the quantum state is mapped on their Zeeman or hyperfine levels with long coherence time. Our solid-state nano-photonic quantum light-matter interfaces can be integrated with other chip-scale photon source and detector devices for multiplexed quantum and classical information processing at the nodes of quantum networks.

Quantum Photonic Devices•Sep 18, 2018•0 citations

Interfacing broadband photonic qubits to on-chip cavity-protected rare-earth ensembles

Tian Zhong, Jonathan M. Kindem, Jake Rochman +1 more

Ensembles of solid-state optical emitters enable broadband quantum storage and transduction of photonic qubits, with applications in high-rate quantum networks for secure communications and interconnecting future quantum computers. To transfer quantum states using ensembles, rephasing techniques are used to mitigate fast decoherence resulting from inhomogeneous broadening, but these techniques generally limit the bandwidth, efficiency and active times of the quantum interface. Here, we use a dense ensemble of neodymium rare-earth ions strongly coupled to a nanophotonic resonator to demonstrate a significant cavity protection effect at the single-photon level-a technique to suppress ensemble decoherence due to inhomogeneous broadening. The protected Rabi oscillations between the cavity field and the atomic super-radiant state enable ultra-fast transfer of photonic frequency qubits to the ions (∼50 GHz bandwidth) followed by retrieval with 98.7% fidelity. With the prospect of coupling to other long-lived rare-earth spin states, this technique opens the possibilities for broadband, always-ready quantum memories and fast optical-to-microwave transducers.

arXiv:1604.00143•Nature Communications•Jan 16, 2017•73 citations

Broadband photonic quantum interface based on a cavity-protected rare-earth ensemble (Conference Presentation)

Tian Zhong, Jonathan M. Kindem, Jake Rochman +1 more

Rare-earth ions doped in crystals are renowned for their excellent coherence properties and large inhomogeneous broadening, which make them ideal for quantum interfaces with broadband photons. These properties have made them one of the leading technologies in quantum optical memories and a promising candidate for optical-to-microwave conversion. To take advantage of the full bandwidth of the rare-earth ensemble, one must overcome the decoherence of a broadband collective excitation due to inhomogeneous broadening. To this end, techniques based on controllable rephasing, such as atomic frequency comb (AFC) or controlled reversible inhomogeneous broadening (CRIB) memories, have been developed with great success. Recently, an alternative method was proposed to suppress the decoherence of an inhomogeneous ensemble via strong coupling to a cavity, a phenomenon called cavity protection. This technique has been demonstrated in the microwave domain with an NV spin ensemble, but has not been demonstrated in the optical domain. Here, we demonstrate cavity protection in the optical domain at the single photon level using an ensemble of rare earths ions coupled to a nanophotonic resonator. The reduction in decoherence due to the cavity-protection effect enables transfer of ultrafast (~50 GHz) frequency qubits into the collective ion excitation and retrieval with 98.7% fidelity. Building on these results to transfer these excitations to long-lived spin states would enable broadband, on-demand quantum memories. Furthermore, this works compliments the work done coupling rare-earths to superconducting resonators in the microwave regime with potential for applications in optical-to-microwave transducers.

•Apr 28, 2017•0 citations

Investigation of quantum information storage in rare earth doped materials

A. L. Alexander

Following the explosion of interest in quantum information processing the field has now reached the point where a quantum memory is becoming a real necessity for further improvements. A quantum memory is fundamentally different from a classical memory due to the "Superposition" principle. Unlike classical information no measurement can be made on the quantum information when it is to be stored. Quantum information is also difficult to store due to its fragile nature and the need to isolate it from the surrounding environment. This thesis describes work that was carried out both to investigate and demonstrate the utility of rare earth ion dopants for quantum memories. Rare earth ion dopants are obvious choices for a quantum memory. Long coherence times in both the optical and hyperfine levels have been observed as well as optical manipulation of the nuclear spin states. The rare earth ions of interest also possess a linear Stark shift which is essential for the quantum memory under investigation here. The scheme investigated here for a quantum memory involves reversible inhomogeneous broadening achieved via macroscopic electric field gradients. The advantage that this scheme has over its competitors is its simplicity. The scheme presented here requires no optical coupling beams and t he only light interacting with the sample is the light to be stored. For that reason the scheme inherently suffers less from noise than other quantum memory proposals. These advantages meant that it was possible to demonstrate the first optical memory using reversible inhomogeneous broadening via macroscopic electric field gradients. The experiments performed in this thesis were in two main areas. The first was characterisation of the hyperfine structure of rare earth ion materials. The second area was demonstrations of reversible inhomogeneous broadening as an optical memory.

•Jan 1, 2007•2 citations
Rare earth ions have exceptionally long coherence times, making them an excellent candidate for quantum information processing. A key part of this processing is quantum state transfer. We demonstrate that high fidelity quantum state transfer between two ensembles of rare earth ions can be achieved by time reversing the connecting optical quantum channel, and suggest using a gradient echo memory to perform this time reversal. We demonstrate that the superradiant coupling between the ensemble of ions and an intermediate cavity coupled to the optical channel can lead to higher transfer fidelities than would otherwise be possible with an individual ion. We suggest increasing the size of the ensemble can overcome unwanted loss and decoherence processes that reduce the transfer fidelity.
Rare-earth ions have exceptionally long coherence times, making them an excellent candidate for quantum information processing. A key part of this processing is quantum state transfer. We show that perfect state transfer can be achieved by time reversing the intermediate quantum channel, and suggest using a gradient echo memory (GEM) to perform this time reversal. We propose an experiment with rare-earth ions to verify these predictions, where an emitter and receiver crystal are connected with an optical channel passed through a GEM. We investigate the effect experimental imperfections and collective dynamics have on the state transfer process. We demonstrate that super-radiant effects can enhance coupling into the optical channel and improve the transfer fidelity. We lastly discuss how our results apply to state transfer of entangled states.
Rare-earth ions doped in crystals are renowned for their excellent coherence properties and large inhomogeneous broadening, which make them ideal for quantum interfaces with broadband photons. These properties have made them one of the leading technologies in quantum optical memories and a promising candidate for optical-to-microwave conversion. To take advantage of the full bandwidth of the rare-earth ensemble, one must overcome the decoherence of a broadband collective excitation due to inhomogeneous broadening. To this end, techniques based on controllable rephasing, such as atomic frequency comb (AFC) or controlled reversible inhomogeneous broadening (CRIB) memories, have been developed with great success. Recently, an alternative method was proposed to suppress the decoherence of an inhomogeneous ensemble via strong coupling to a cavity, a phenomenon called cavity protection. This technique has been demonstrated in the microwave domain with an NV spin ensemble, but has not been demonstrated in the optical domain. Here, we demonstrate cavity protection in the optical domain at the single photon level using an ensemble of rare earths ions coupled to a nanophotonic resonator. The reduction in decoherence due to the cavity-protection effect enables transfer of ultrafast (~50 GHz) frequency qubits into the collective ion excitation and retrieval with 98.7% fidelity. Building on these results to transfer these excitations to long-lived spin states would enable broadband, on-demand quantum memories. Furthermore, this works compliments the work done coupling rare-earths to superconducting resonators in the microwave regime with potential for applications in optical-to-microwave transducers.
I present quantum nano-photonic devices based on nanophotonic resonators coupled to rare-earth-ions in crystals. The rare-earth ions exhibit long coherence times on optical transitions, which makes them suitable for optical quantum memories. We demonstrate a high-fidelity nanophotonic quantum memory based on a mesoscopic rare-earth ensemble coupled to a photonic crystal cavity. The nanocavity enables >95% spin polarization for efficient initialization of the atomic frequency comb memory, and time-bin-selective readout via enhanced optical Stark shift of the comb frequencies. Besides ensemble memories, single rare-earth-ions coupled to nano-resonators can be used as single optically addressable quantum bits where the quantum state is mapped on their Zeeman or hyperfine levels with long coherence time. Our solid-state nano-photonic quantum light-matter interfaces can be integrated with other chip-scale photon source and detector devices for multiplexed quantum and classical information processing at the nodes of quantum networks.
Ensembles of solid-state optical emitters enable broadband quantum storage and transduction of photonic qubits, with applications in high-rate quantum networks for secure communications and interconnecting future quantum computers. To transfer quantum states using ensembles, rephasing techniques are used to mitigate fast decoherence resulting from inhomogeneous broadening, but these techniques generally limit the bandwidth, efficiency and active times of the quantum interface. Here, we use a dense ensemble of neodymium rare-earth ions strongly coupled to a nanophotonic resonator to demonstrate a significant cavity protection effect at the single-photon level-a technique to suppress ensemble decoherence due to inhomogeneous broadening. The protected Rabi oscillations between the cavity field and the atomic super-radiant state enable ultra-fast transfer of photonic frequency qubits to the ions (∼50 GHz bandwidth) followed by retrieval with 98.7% fidelity. With the prospect of coupling to other long-lived rare-earth spin states, this technique opens the possibilities for broadband, always-ready quantum memories and fast optical-to-microwave transducers.
Rare-earth ions doped in crystals are renowned for their excellent coherence properties and large inhomogeneous broadening, which make them ideal for quantum interfaces with broadband photons. These properties have made them one of the leading technologies in quantum optical memories and a promising candidate for optical-to-microwave conversion. To take advantage of the full bandwidth of the rare-earth ensemble, one must overcome the decoherence of a broadband collective excitation due to inhomogeneous broadening. To this end, techniques based on controllable rephasing, such as atomic frequency comb (AFC) or controlled reversible inhomogeneous broadening (CRIB) memories, have been developed with great success. Recently, an alternative method was proposed to suppress the decoherence of an inhomogeneous ensemble via strong coupling to a cavity, a phenomenon called cavity protection. This technique has been demonstrated in the microwave domain with an NV spin ensemble, but has not been demonstrated in the optical domain. Here, we demonstrate cavity protection in the optical domain at the single photon level using an ensemble of rare earths ions coupled to a nanophotonic resonator. The reduction in decoherence due to the cavity-protection effect enables transfer of ultrafast (~50 GHz) frequency qubits into the collective ion excitation and retrieval with 98.7% fidelity. Building on these results to transfer these excitations to long-lived spin states would enable broadband, on-demand quantum memories. Furthermore, this works compliments the work done coupling rare-earths to superconducting resonators in the microwave regime with potential for applications in optical-to-microwave transducers.
Following the explosion of interest in quantum information processing the field has now reached the point where a quantum memory is becoming a real necessity for further improvements. A quantum memory is fundamentally different from a classical memory due to the "Superposition" principle. Unlike classical information no measurement can be made on the quantum information when it is to be stored. Quantum information is also difficult to store due to its fragile nature and the need to isolate it from the surrounding environment. This thesis describes work that was carried out both to investigate and demonstrate the utility of rare earth ion dopants for quantum memories. Rare earth ion dopants are obvious choices for a quantum memory. Long coherence times in both the optical and hyperfine levels have been observed as well as optical manipulation of the nuclear spin states. The rare earth ions of interest also possess a linear Stark shift which is essential for the quantum memory under investigation here. The scheme investigated here for a quantum memory involves reversible inhomogeneous broadening achieved via macroscopic electric field gradients. The advantage that this scheme has over its competitors is its simplicity. The scheme presented here requires no optical coupling beams and t he only light interacting with the sample is the light to be stored. For that reason the scheme inherently suffers less from noise than other quantum memory proposals. These advantages meant that it was possible to demonstrate the first optical memory using reversible inhomogeneous broadening via macroscopic electric field gradients. The experiments performed in this thesis were in two main areas. The first was characterisation of the hyperfine structure of rare earth ion materials. The second area was demonstrations of reversible inhomogeneous broadening as an optical memory.