### 373 results for qubit oscillator frequency

Contributors: Johnson, Kale Gifford

Date: 2016-01-01

Since the dawn of quantum information science, laser-cooled trapped atomic ions have been one of the most compelling systems for the physical realization of a quantum computer. By applying **qubit** state dependent forces to the ions, their collective motional modes can be used as a bus to realize entangling quantum gates. Ultrafast state-dependent kicks [1] can provide a universal set of quantum logic operations, in conjunction with ultrafast single **qubit** rotations [2], which uses only ultrafast laser pulses. This may present a clearer route to scaling a trapped ion processor [3]. In addition to the role that spin-dependent kicks (SDKs) play in quantum computation, their utility in fundamental quantum mechanics research is also apparent. In this thesis, we present a set of experiments which demonstrate some of the principle properties of SDKs including ion motion independence (we demonstrate single ion thermometry from the ground state to near room temperature and the largest Schrodinger cat state ever created in an **oscillator**), high speed operations (compared with conventional atom-laser interactions), and multi-**qubit** entanglement operations with speed that is not fundamentally limited by the trap **oscillation** **frequency**. We also present a method to provide higher stability in the radial mode ion **oscillation** **frequencies** of a linear radiofrequency (rf) Paul trap--a crucial factor when performing operations on the rf-sensitive modes. Finally, we present the highest atomic position sensitivity measurement of an isolated atom to date of ~0.5 nm Hz^(-1/2) with a minimum uncertainty of 1.7 nm using a 0.6 numerical aperature (NA) lens system, along with a method to correct aberrations and a direct position measurement of ion micromotion (the inherent **oscillations** of an ion trapped in an **oscillating** rf field). This development could be used to directly image atom motion in the quantum regime, along with sensing forces at the yoctonewton [10^(-24) N)] scale for gravity sensing, and 3D imaging of atoms from static to higher **frequency** motion. These ultrafast atomic **qubit** manipulation tools demonstrate inherent advantages over conventional techniques, offering a fundamentally distinct regime of control and speed not previously achievable. ... Since the dawn of quantum information science, laser-cooled trapped atomic ions have been one of the most compelling systems for the physical realization of a quantum computer. By applying **qubit** state dependent forces to the ions, their collective motional modes can be used as a bus to realize entangling quantum gates. Ultrafast state-dependent kicks [1] can provide a universal set of quantum logic operations, in conjunction with ultrafast single **qubit** rotations [2], which uses only ultrafast laser pulses. This may present a clearer route to scaling a trapped ion processor [3]. In addition to the role that spin-dependent kicks (SDKs) play in quantum computation, their utility in fundamental quantum mechanics research is also apparent. In this thesis, we present a set of experiments which demonstrate some of the principle properties of SDKs including ion motion independence (we demonstrate single ion thermometry from the ground state to near room temperature and the largest Schrodinger cat state ever created in an **oscillator**), high speed operations (compared with conventional atom-laser interactions), and multi-**qubit** entanglement operations with speed that is not fundamentally limited by the trap **oscillation** **frequency**. We also present a method to provide higher stability in the radial mode ion **oscillation** **frequencies** of a linear radiofrequency (rf) Paul trap--a crucial factor when performing operations on the rf-sensitive modes. Finally, we present the highest atomic position sensitivity measurement of an isolated atom to date of ~0.5 nm Hz^(-1/2) with a minimum uncertainty of 1.7 nm using a 0.6 numerical aperature (NA) lens system, along with a method to correct aberrations and a direct position measurement of ion micromotion (the inherent **oscillations** of an ion trapped in an **oscillating** rf field). This development could be used to directly image atom motion in the quantum regime, along with sensing forces at the yoctonewton [10^(-24) N)] scale for gravity sensing, and 3D imaging of atoms from static to higher **frequency** motion. These ultrafast atomic **qubit** manipulation tools demonstrate inherent advantages over conventional techniques, offering a fundamentally distinct regime of control and speed not previously achievable.

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Contributors: Suri, Baladitya

Date: 2015-01-01

Superconducting **qubits**...I discuss the design, fabrication and measurement at millikelvin-temperatures of Al/AlO$_x$/Al Josephson junction-based transmon **qubits** coupled to superconducting thin-film lumped element microwave resonators made of aluminum on sapphire. The resonators had a center **frequency** of around $6\,$GHz, and a total quality factor ranging from 15,000 to 70,000 for the various devices. The area of the transmon junctions was about $150\, \mathrm{nm} \times 150\, \mathrm{nm}$ and with Josephson energy $E_J$ such that $10\,\text{GHz} \leq E_J / h \leq 30\,$GHz. The charging energy of the transmons arising mostly from the large interdigital shunt capacitance, was $E_c / h \approx 300\,$MHz.
I present microwave spectroscopy of the devices in the strongly dispersive regime of circuit quantum electrodynamics. In this limit the ac Stark shift due to a single photon in the resonator is greater than the linewidth of the **qubit** transition. When the resonator is driven coherently using a coupler tone, the transmon spectrum reveals individual ``photon number'' peaks, each corresponding to a single additional photon in the resonator. Using a weighted average of the peak heights in the **qubit** spectrum, I calculated the average number of photons $\bar{n}$ in the resonator. I also observed a nonlinear variation of $\bar{n}$ with the applied power of the coupler tone $P_{rf}$. I studied this nonlinearity using numerical simulations and found good qualitative agreement with data.
In the absence of a coherent drive on the resonator, a thermal population of $5.474\,$GHz photons in the resonator, at an effective temperature of $120\,$mK resulted in a weak $n=1$ thermal photon peak in the **qubit** spectrum. In the presence of independent coupler and probe tones, the $n=1$ thermal photon peak revealed an Autler-Townes splitting. The observed effect was explained accurately using the four lowest levels of the dispersively dressed Jaynes-Cummings transmon-resonator system, and numerical simulations of the steady-state master equation for the coupled system.
I also present time-domain measurements on transmons coupled to lumped-element resonators. From $T_1$ and Rabi **oscillation** measurements, I found that my early transmon devices (called design LEv5) had lifetimes ($T_1 \sim 1\,\mu$s) limited by strong coupling to the $50\,\Omega$ transmission line. This coupling was characterized by the the rate of change of the Rabi **oscillation** **frequency** with the change in the drive voltage ($\mathrm{d}f_{Rabi}\, / \mathrm{d}V$) -- also termed the Rabi coupling to the drive. I studied the design of the transmon-resonator system using circuit analysis and microwave simulations with the aim being to reduce the Rabi coupling to the drive. By increasing the resonance **frequency** of the resonator $\omega_r/2\pi$ from 5.4$\,$GHz to 7.2$\,$GHz, lowering the coupling of the resonator to the transmission line and thereby increasing the external quality factor $Q_e$ from 20,000 to 70,000, and reducing the transmon-resonator coupling $g/2\pi$ from 70$\,$MHz to 40$\,$MHz, I reduced the Rabi coupling to the drive by an order of magnitude ($\sim$ factor of 20). The $T_1 \sim 4\,\mu$s of devices in the new design (LEv6) was longer than that of the early devices, but still much shorter than the lifetimes predicted from Rabi coupling, suggesting the presence of alternative sources of noise causing **qubit** relaxation. Microwave simulations and circuit analysis in the presence of a dielectric loss tangent $\tan \delta \simeq 5\times10^{-6}$ agree reasonably well with the measured $T_1$ values, suggesting that surface dielectric loss may be causing relaxation of transmons in the new designs. ... I discuss the design, fabrication and measurement at millikelvin-temperatures of Al/AlO$_x$/Al Josephson junction-based transmon **qubits** coupled to superconducting thin-film lumped element microwave resonators made of aluminum on sapphire. The resonators had a center **frequency** of around $6\,$GHz, and a total quality factor ranging from 15,000 to 70,000 for the various devices. The area of the transmon junctions was about $150\, \mathrm{nm} \times 150\, \mathrm{nm}$ and with Josephson energy $E_J$ such that $10\,\text{GHz} \leq E_J / h \leq 30\,$GHz. The charging energy of the transmons arising mostly from the large interdigital shunt capacitance, was $E_c / h \approx 300\,$MHz.
I present microwave spectroscopy of the devices in the strongly dispersive regime of circuit quantum electrodynamics. In this limit the ac Stark shift due to a single photon in the resonator is greater than the linewidth of the **qubit** transition. When the resonator is driven coherently using a coupler tone, the transmon spectrum reveals individual ``photon number'' peaks, each corresponding to a single additional photon in the resonator. Using a weighted average of the peak heights in the **qubit** spectrum, I calculated the average number of photons $\bar{n}$ in the resonator. I also observed a nonlinear variation of $\bar{n}$ with the applied power of the coupler tone $P_{rf}$. I studied this nonlinearity using numerical simulations and found good qualitative agreement with data.
In the absence of a coherent drive on the resonator, a thermal population of $5.474\,$GHz photons in the resonator, at an effective temperature of $120\,$mK resulted in a weak $n=1$ thermal photon peak in the **qubit** spectrum. In the presence of independent coupler and probe tones, the $n=1$ thermal photon peak revealed an Autler-Townes splitting. The observed effect was explained accurately using the four lowest levels of the dispersively dressed Jaynes-Cummings transmon-resonator system, and numerical simulations of the steady-state master equation for the coupled system.
I also present time-domain measurements on transmons coupled to lumped-element resonators. From $T_1$ and Rabi **oscillation** measurements, I found that my early transmon devices (called design LEv5) had lifetimes ($T_1 \sim 1\,\mu$s) limited by strong coupling to the $50\,\Omega$ transmission line. This coupling was characterized by the the rate of change of the Rabi **oscillation** **frequency** with the change in the drive voltage ($\mathrm{d}f_{Rabi}\, / \mathrm{d}V$) -- also termed the Rabi coupling to the drive. I studied the design of the transmon-resonator system using circuit analysis and microwave simulations with the aim being to reduce the Rabi coupling to the drive. By increasing the resonance **frequency** of the resonator $\omega_r/2\pi$ from 5.4$\,$GHz to 7.2$\,$GHz, lowering the coupling of the resonator to the transmission line and thereby increasing the external quality factor $Q_e$ from 20,000 to 70,000, and reducing the transmon-resonator coupling $g/2\pi$ from 70$\,$MHz to 40$\,$MHz, I reduced the Rabi coupling to the drive by an order of magnitude ($\sim$ factor of 20). The $T_1 \sim 4\,\mu$s of devices in the new design (LEv6) was longer than that of the early devices, but still much shorter than the lifetimes predicted from Rabi coupling, suggesting the presence of alternative sources of noise causing **qubit** relaxation. Microwave simulations and circuit analysis in the presence of a dielectric loss tangent $\tan \delta \simeq 5\times10^{-6}$ agree reasonably well with the measured $T_1$ values, suggesting that surface dielectric loss may be causing relaxation of transmons in the new designs.

Data types:

Contributors: Wigger, Daniel, Schneider, Christian, Gerhardt, Stefan, Kamp, Martin, Höfling, Sven, Kuhn, Tilmann, Kasprzak, Jacek

Date: 2018-01-01

While the advanced coherent control of **qubits** is now routinely carried out in low **frequency** (GHz) systems like single spins, it is far more challenging to achieve for two-level systems in the optical domain. This is because the latter evolve typically in the THz range, calling for tools of ultrafast, coherent, nonlinear optics. Using four-wave mixing micro-spectroscopy, we here measure the optically driven Bloch vector dynamics of a single exciton confined in a semiconductor quantum dot. In a combined experimental and theoretical approach, we reveal the intrinsic Rabi **oscillation** dynamics by monitoring both central exciton quantities, i.e., its occupation and the microscopic coherence, as resolved by the four-wave mixing technique. In the **frequency** domain this **oscillation** generates the Autler-Townes splitting of the light-exciton dressed states, directly seen in the four-wave mixing spectra. We further demonstrate that the coupling to acoustic phonons strongly influences the FWM dynamics on the picosecond timescale, because it leads to transitions between the dressed states. ... While the advanced coherent control of **qubits** is now routinely carried out in low **frequency** (GHz) systems like single spins, it is far more challenging to achieve for two-level systems in the optical domain. This is because the latter evolve typically in the THz range, calling for tools of ultrafast, coherent, nonlinear optics. Using four-wave mixing micro-spectroscopy, we here measure the optically driven Bloch vector dynamics of a single exciton confined in a semiconductor quantum dot. In a combined experimental and theoretical approach, we reveal the intrinsic Rabi **oscillation** dynamics by monitoring both central exciton quantities, i.e., its occupation and the microscopic coherence, as resolved by the four-wave mixing technique. In the **frequency** domain this **oscillation** generates the Autler-Townes splitting of the light-exciton dressed states, directly seen in the four-wave mixing spectra. We further demonstrate that the coupling to acoustic phonons strongly influences the FWM dynamics on the picosecond timescale, because it leads to transitions between the dressed states.

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Contributors: Wigger, Daniel, Schneider, Christian, Gerhardt, Stefan, Kamp, Martin, Höfling, Sven, Kuhn, Tilmann, Kasprzak, Jacek

Date: 2018-01-01

While the advanced coherent control of **qubits** is now routinely carried out in low **frequency** (GHz) systems like single spins, it is far more challenging to achieve for two-level systems in the optical domain. This is because the latter evolve typically in the THz range, calling for tools of ultrafast, coherent, nonlinear optics. Using four-wave mixing micro-spectroscopy, we here measure the optically driven Bloch vector dynamics of a single exciton confined in a semiconductor quantum dot. In a combined experimental and theoretical approach, we reveal the intrinsic Rabi **oscillation** dynamics by monitoring both central exciton quantities, i.e., its occupation and the microscopic coherence, as resolved by the four-wave mixing technique. In the **frequency** domain this **oscillation** generates the Autler-Townes splitting of the light-exciton dressed states, directly seen in the four-wave mixing spectra. We further demonstrate that the coupling to acoustic phonons strongly influences the FWM dynamics on the picosecond timescale, because it leads to transitions between the dressed states. ... While the advanced coherent control of **qubits** is now routinely carried out in low **frequency** (GHz) systems like single spins, it is far more challenging to achieve for two-level systems in the optical domain. This is because the latter evolve typically in the THz range, calling for tools of ultrafast, coherent, nonlinear optics. Using four-wave mixing micro-spectroscopy, we here measure the optically driven Bloch vector dynamics of a single exciton confined in a semiconductor quantum dot. In a combined experimental and theoretical approach, we reveal the intrinsic Rabi **oscillation** dynamics by monitoring both central exciton quantities, i.e., its occupation and the microscopic coherence, as resolved by the four-wave mixing technique. In the **frequency** domain this **oscillation** generates the Autler-Townes splitting of the light-exciton dressed states, directly seen in the four-wave mixing spectra. We further demonstrate that the coupling to acoustic phonons strongly influences the FWM dynamics on the picosecond timescale, because it leads to transitions between the dressed states.

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Contributors: Carolan, Jacques, Uttara Chakraborty, Harris, Nicholas, Mihir Pant, Baehr-Jones, Thomas, Hochberg, Michael, Englund, Dirk

Date: 2019-01-01

Large-scale quantum technologies require exquisite control over many individual quantum systems. Typically, such systems are very sensitive to environmental fluctuations, and diagnosing errors via measurements causes unavoidable perturbations. In this work we present an in situ **frequency** locking technique that monitors and corrects **frequency** variations in single photon sources based on microring resonators. By using the same classical laser fields required for photon generation as a probe to diagnose variations in the resonator **frequency**, our protocol applies feedback control to correct photon **frequency** errors in parallel to the optical quantum computation without disturbing the physical **qubit**. We implement our technique on a silicon photonic device and demonstrate sub 1 pm **frequency** stabilization in the presence of applied environmental noise, corresponding to a fractional **frequency** drift of <1% of a photon linewidth. Using these methods we demonstrate feedback controlled quantum state engineering. By distributing a single local **oscillator** across a single chip or network of chips, our approach enables **frequency** locking of many single photon sources for large-scale photonic quantum technologies. ... Large-scale quantum technologies require exquisite control over many individual quantum systems. Typically, such systems are very sensitive to environmental fluctuations, and diagnosing errors via measurements causes unavoidable perturbations. In this work we present an in situ **frequency** locking technique that monitors and corrects **frequency** variations in single photon sources based on microring resonators. By using the same classical laser fields required for photon generation as a probe to diagnose variations in the resonator **frequency**, our protocol applies feedback control to correct photon **frequency** errors in parallel to the optical quantum computation without disturbing the physical **qubit**. We implement our technique on a silicon photonic device and demonstrate sub 1 pm **frequency** stabilization in the presence of applied environmental noise, corresponding to a fractional **frequency** drift of <1% of a photon linewidth. Using these methods we demonstrate feedback controlled quantum state engineering. By distributing a single local **oscillator** across a single chip or network of chips, our approach enables **frequency** locking of many single photon sources for large-scale photonic quantum technologies.

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Contributors: Carolan, Jacques, Uttara Chakraborty, Harris, Nicholas, Mihir Pant, Baehr-Jones, Thomas, Hochberg, Michael, Englund, Dirk

Date: 2019-01-01

Large-scale quantum technologies require exquisite control over many individual quantum systems. Typically, such systems are very sensitive to environmental fluctuations, and diagnosing errors via measurements causes unavoidable perturbations. In this work we present an in situ **frequency** locking technique that monitors and corrects **frequency** variations in single photon sources based on microring resonators. By using the same classical laser fields required for photon generation as a probe to diagnose variations in the resonator **frequency**, our protocol applies feedback control to correct photon **frequency** errors in parallel to the optical quantum computation without disturbing the physical **qubit**. We implement our technique on a silicon photonic device and demonstrate sub 1 pm **frequency** stabilization in the presence of applied environmental noise, corresponding to a fractional **frequency** drift of <1% of a photon linewidth. Using these methods we demonstrate feedback controlled quantum state engineering. By distributing a single local **oscillator** across a single chip or network of chips, our approach enables **frequency** locking of many single photon sources for large-scale photonic quantum technologies. ... Large-scale quantum technologies require exquisite control over many individual quantum systems. Typically, such systems are very sensitive to environmental fluctuations, and diagnosing errors via measurements causes unavoidable perturbations. In this work we present an in situ **frequency** locking technique that monitors and corrects **frequency** variations in single photon sources based on microring resonators. By using the same classical laser fields required for photon generation as a probe to diagnose variations in the resonator **frequency**, our protocol applies feedback control to correct photon **frequency** errors in parallel to the optical quantum computation without disturbing the physical **qubit**. We implement our technique on a silicon photonic device and demonstrate sub 1 pm **frequency** stabilization in the presence of applied environmental noise, corresponding to a fractional **frequency** drift of <1% of a photon linewidth. Using these methods we demonstrate feedback controlled quantum state engineering. By distributing a single local **oscillator** across a single chip or network of chips, our approach enables **frequency** locking of many single photon sources for large-scale photonic quantum technologies.

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Contributors: Hsuan-Hao Lu, Lukens, Joseph, Peters, Nicholas, Williams, Brian, Weiner, Andrew, Lougovski, Pavel

Date: 2018-01-01

We implement distinct quantum gates in parallel on two entangled **frequency**-bin **qubits** for the first time. Our basic quantum operation controls the spectral overlap between adjacent **frequency** bins, allowing us to observe **frequency**-bin Hong-Ou-Mandel interference with a visibility of 0.971±0.007, a record for two photons of different colors. By integrating this tunability with **frequency** parallelization, we synthesize independent gates on entangled **qubits** in the same optical fiber and flip their spectral correlations. The ultralow noise of our gates preserves entanglement purity, as evidenced by a 9.8σ violation of an entropic separability bound. Our results constitute the first closed, user-defined gates on **frequency**-bin **qubits** in parallel, with application to the development of **frequency**-based quantum information processing. ... We implement distinct quantum gates in parallel on two entangled **frequency**-bin **qubits** for the first time. Our basic quantum operation controls the spectral overlap between adjacent **frequency** bins, allowing us to observe **frequency**-bin Hong-Ou-Mandel interference with a visibility of 0.971±0.007, a record for two photons of different colors. By integrating this tunability with **frequency** parallelization, we synthesize independent gates on entangled **qubits** in the same optical fiber and flip their spectral correlations. The ultralow noise of our gates preserves entanglement purity, as evidenced by a 9.8σ violation of an entropic separability bound. Our results constitute the first closed, user-defined gates on **frequency**-bin **qubits** in parallel, with application to the development of **frequency**-based quantum information processing.

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Contributors: Hsuan-Hao Lu, Lukens, Joseph, Peters, Nicholas, Williams, Brian, Weiner, Andrew, Lougovski, Pavel

Date: 2018-01-01

We implement distinct quantum gates in parallel on two entangled **frequency**-bin **qubits** for the first time. Our basic quantum operation controls the spectral overlap between adjacent **frequency** bins, allowing us to observe **frequency**-bin Hong-Ou-Mandel interference with a visibility of 0.971±0.007, a record for two photons of different colors. By integrating this tunability with **frequency** parallelization, we synthesize independent gates on entangled **qubits** in the same optical fiber and flip their spectral correlations. The ultralow noise of our gates preserves entanglement purity, as evidenced by a 9.8σ violation of an entropic separability bound. Our results constitute the first closed, user-defined gates on **frequency**-bin **qubits** in parallel, with application to the development of **frequency**-based quantum information processing. ... We implement distinct quantum gates in parallel on two entangled **frequency**-bin **qubits** for the first time. Our basic quantum operation controls the spectral overlap between adjacent **frequency** bins, allowing us to observe **frequency**-bin Hong-Ou-Mandel interference with a visibility of 0.971±0.007, a record for two photons of different colors. By integrating this tunability with **frequency** parallelization, we synthesize independent gates on entangled **qubits** in the same optical fiber and flip their spectral correlations. The ultralow noise of our gates preserves entanglement purity, as evidenced by a 9.8σ violation of an entropic separability bound. Our results constitute the first closed, user-defined gates on **frequency**-bin **qubits** in parallel, with application to the development of **frequency**-based quantum information processing.

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Contributors: Lukens, Joseph M., Lougovski, Pavel

Date: 2017-01-01

Among the objectives for large-scale quantum computation is the quantum interconnect: a device that uses photons to interface **qubits** that otherwise could not interact. However, the current approaches require photons indistinguishable in **frequency**—a major challenge for systems experiencing different local environments or of different physical compositions altogether. Here, we develop an entirely new platform that actually exploits such **frequency** mismatch for processing quantum information. Labeled “spectral linear optical quantum computation” (spectral LOQC), our protocol offers favorable linear scaling of optical resources and enjoys an unprecedented degree of parallelism, as an arbitrary N-**qubit** quantum gate may be performed in parallel on multiple N-**qubit** sets in the same linear optical device. Not only does spectral LOQC offer new potential for optical interconnects, but it also brings the ubiquitous technology of high-speed fiber optics to bear on photonic quantum information, making wavelength-configurable and robust optical quantum systems within reach. ... Among the objectives for large-scale quantum computation is the quantum interconnect: a device that uses photons to interface **qubits** that otherwise could not interact. However, the current approaches require photons indistinguishable in **frequency**—a major challenge for systems experiencing different local environments or of different physical compositions altogether. Here, we develop an entirely new platform that actually exploits such **frequency** mismatch for processing quantum information. Labeled “spectral linear optical quantum computation” (spectral LOQC), our protocol offers favorable linear scaling of optical resources and enjoys an unprecedented degree of parallelism, as an arbitrary N-**qubit** quantum gate may be performed in parallel on multiple N-**qubit** sets in the same linear optical device. Not only does spectral LOQC offer new potential for optical interconnects, but it also brings the ubiquitous technology of high-speed fiber optics to bear on photonic quantum information, making wavelength-configurable and robust optical quantum systems within reach.

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Contributors: Lukens, Joseph M., Lougovski, Pavel

Date: 2017-01-01

Among the objectives for large-scale quantum computation is the quantum interconnect: a device that uses photons to interface **qubits** that otherwise could not interact. However, the current approaches require photons indistinguishable in **frequency**—a major challenge for systems experiencing different local environments or of different physical compositions altogether. Here, we develop an entirely new platform that actually exploits such **frequency** mismatch for processing quantum information. Labeled “spectral linear optical quantum computation” (spectral LOQC), our protocol offers favorable linear scaling of optical resources and enjoys an unprecedented degree of parallelism, as an arbitrary N-**qubit** quantum gate may be performed in parallel on multiple N-**qubit** sets in the same linear optical device. Not only does spectral LOQC offer new potential for optical interconnects, but it also brings the ubiquitous technology of high-speed fiber optics to bear on photonic quantum information, making wavelength-configurable and robust optical quantum systems within reach. ... Among the objectives for large-scale quantum computation is the quantum interconnect: a device that uses photons to interface **qubits** that otherwise could not interact. However, the current approaches require photons indistinguishable in **frequency**—a major challenge for systems experiencing different local environments or of different physical compositions altogether. Here, we develop an entirely new platform that actually exploits such **frequency** mismatch for processing quantum information. Labeled “spectral linear optical quantum computation” (spectral LOQC), our protocol offers favorable linear scaling of optical resources and enjoys an unprecedented degree of parallelism, as an arbitrary N-**qubit** quantum gate may be performed in parallel on multiple N-**qubit** sets in the same linear optical device. Not only does spectral LOQC offer new potential for optical interconnects, but it also brings the ubiquitous technology of high-speed fiber optics to bear on photonic quantum information, making wavelength-configurable and robust optical quantum systems within reach.

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