Generating Multimode Entangled Microwaves with a Superconducting Parametric Cavity

Chang, Christophe; Simoen, Michael Roger Andre; Aumentado, José; Sabín, Carlos; Forn-Díaz, P.; Vadiraj, A. M.; Quijandría, Fernando; Johansson, Göran; Fuentes, Ivette; Wilson, Christopher

doi:10.1103/physrevapplied.10.044019

Cited by 49 publications

(21 citation statements)

References 45 publications

(57 reference statements)

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“…Further, we can produce a hybrid version to two modes, where two photons are degenerate and one is nondegenerate. Our triplet source is bright, producing a propagating photon flux with a flux density controllable from less than 1 to greater than 60 photon/s/Hz over a bandwidth of hundreds of kHz, well surpassing any records to date for photon triplets and comparable to ordinary two-photon downconversion (TPDC) experiments arXiv:1907.08692v1 [quant-ph] 19 Jul 2019 [37,38]. The high flux allowed us to perform detailed analysis of the novel phase-space distributions and strongly non-Gaussian statistics of the states.…”

Section: Introductionmentioning

confidence: 87%

“…The system is absolutely calibrated using a shot noise tunnel junction, as described in detail in Ref. [38], giving calibrated values for the system gain, the system noise temperature, and the physical temperature of the input state. The amplified signal is split at room temperature and the three modes are measured simultaneously using heterodyne detection, giving the field quadratures for the modes.…”

Section: A Three-photon Spdc To a Single Modementioning

confidence: 99%

“…The fundamental mode has a relatively low frequency of around 1 GHz such that there are three higher-order modes accessible within our 4-8 GHz measurement bandwidth. Impedance engineering [38,46,47] is used to make the mode spacing nondegenerate, yielding mode frequencies of approximately 4, 6 and 7 GHz. Parametric processes are driven by a microwave pump inductively coupled to the SQUID, modulating the boundary condition of the cavity.…”

Section: Introductionmentioning

confidence: 99%

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Observation of Three-Photon Spontaneous Parametric Down-Conversion in a Superconducting Parametric Cavity

et al. 2020

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Spontaneous parametric downconversion (SPDC) has been a key enabling technology in exploring quantum phenomena and their applications for decades. For instance, traditional SPDC, which splits a high energy pump photon into two lower energy photons, is a common way to produce entangled photon pairs. Since the early realizations of SPDC, researchers have thought to generalize it to higher order, e.g., to produce entangled photon triplets. However, directly generating photon triplets through a single SPDC process has remained elusive. Here, using a flux-pumped superconducting parametric cavity, we demonstrate direct three-photon SPDC, with photon triplets generated in a single cavity mode or split between multiple modes. With strong pumping, the states can be quite bright, with flux densities exceeding 60 photon/s/Hz. The observed states are strongly non-Gaussian, which has important implications for potential applications. In the single-mode case, we observe a triangular star-shaped distribution of quadrature voltages, indicative of the longpredicted "star state". The observed star state shows strong third-order correlations, as expected for a state generated by a cubic Hamiltonian. By pumping at the sum frequency of multiple modes, we observe strong three-body correlations between multiple modes, strikingly, in the absence of secondorder correlations. We further analyze the third-order correlations under mode transformations by the symplectic symmetry group, showing that the observed transformation properties serve to "fingerprint" the specific cubic Hamiltonian that generates them. The observed non-Gaussian, thirdorder correlations represent an important step forward in quantum optics and may have a strong impact on quantum communication with microwave fields as well as continuous-variable quantum computation.

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Section: Introductionmentioning

confidence: 87%

Section: A Three-photon Spdc To a Single Modementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Observation of Three-Photon Spontaneous Parametric Down-Conversion in a Superconducting Parametric Cavity

et al. 2020

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“…Nonetheless, for pure states, full N -partite inseparability is sufficient to imply genuine N -partite entanglement. Experiments have confirmed both full Npartite inseparability [19][20][21][22][23] and genuine N -partite entanglement (N ≥ 3) for CV systems [13,[24][25][26][27]. Here, "continuous variable (CV)" refers to the use of measurements that have continuous-variable outcomes e.g.…”

Section: Introductionmentioning

confidence: 99%

Criteria to detect genuine multipartite entanglement using spin measurements

Teh

Reid

2019

Phys. Rev. A

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We derive conditions in the form of inequalities to detect the genuine N -partite entanglement of N systems. The inequalities are expressed in terms of variances of spin operators, and can be tested by local spin measurements performed on the individual systems. Violation of the inequalities is sufficient (but not necessary) to certify the multipartite entanglement, and occurs when a type of spin squeezing is created. The inequalities are similar to those derived for continuous-variable systems, but instead are based on the Heisenberg spin-uncertainty relation ∆Jx∆Jy ≥ | Jz |/2. We also extend previous work to derive spin-variance inequalities that certify the full tripartite inseparability or genuine multi-partite entanglement among systems with fixed spin J, as in Greenberger-Horne-Zeilinger (GHZ) states and W states where J = 1/2. These inequalities are derived from the planar spin-uncertainty relation (∆Jx) 2 + (∆Jy) 2 ≥ CJ where CJ is a constant for each J. Finally, it is shown how the inequalities detect multipartite entanglement based on Stokes operators. We illustrate with experiments that create entanglement shared among separated atomic ensembles, polarization-entangled optical modes, and the clouds of atoms of an expanding spin-squeezed Bose-Einstein condensate. For each example, we give a criterion to certify the mutual entanglement.

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“…9-11 This coupling can be extended beyond the strong coupling regime to ultrastrong domains. 12 But, with the addition of more qubits the system would not be completely robust.We use a modified superconducting coplanar waveguide resonator (CWR) as a multimode microwave photon quantum bus, [13][14][15][16] to which we apply quantum reservoir engineering, to create two-mode entangled microwave fields as the interaction medium. The microwave fields can be affected by the decoherence from the surrounding qubits, which make them less effective in transferring states within the system.…”

mentioning

confidence: 99%

Hybrid spin-superconducting quantum circuit mediated by deterministically prepared entangled photonic states

Mathieson

Bhattacharyya

2019

AIP Advances

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In hybrid quantum systems a controllable coupling can be obtained by mediating the interactions with dynamically introduced photons. We propose a hybrid quantum architecture consisting of two nitrogen vacancy center ensembles coupled to a tunable flux qubit; that are contained on the transmission line of a multimode nonlinear superconducting coplanar waveguide resonator with an appended Josephson mixing device. We discuss using entangled propagating microwaves photons, which through our nonlinear wave-mixing procedure are made into macroscopically distinct quantum states. We use these states to steer the system and show that with further amplification we can create a similar photonic state, which has a more distinct reduction of its uncertainty. Furthermore, we show that all of this leads to a lengthened coherence time, a reasonable fidelity which decays to 0.94 and then later increases upward to stabilize at 0.6 as well as a strengthened entanglement.Hybrid quantum systems have emerged as a potential solution, due to the properties which the interface between the different components can provide as an open quantum system. 1,2 Nitrogen vacancy center ensembles (NVEs) have been of importance due to their ability to be coupled and their stability in an open system. [3][4][5][6][7][8] Various studies have been done involving them collectively coupled to a flux qubit (FQ). 9-11 This coupling can be extended beyond the strong coupling regime to ultrastrong domains. 12 But, with the addition of more qubits the system would not be completely robust.We use a modified superconducting coplanar waveguide resonator (CWR) as a multimode microwave photon quantum bus, [13][14][15][16] to which we apply quantum reservoir engineering, to create two-mode entangled microwave fields as the interaction medium. The microwave fields can be affected by the decoherence from the surrounding qubits, which make them less effective in transferring states within the system. One way to strengthen both the system and the microwave fields and make them less susceptible to dissipation is through transforming them into nonclassical states, 17-19 such as a coherent superposition state or Schrödinger cat state. 20 We look at the degree of squeezing applied and attempt to extend the work of Minganti et al. 21 and Hacker et al. 22 , which suggested the inherent squeezing of coherent cat states and a method of deterministically generating cat states. 23 We look at a Schrödinger cat-like state, which in our system. This state has been explored because of its ability to suppress noise, which can lead to more precise measurements, such as in quantum enhanced sensing. 24 In our study, we look at cases involving a systematic creation and distribution of coherent and squeezed coherent macroscopically distinct states by the multimode parametric waveguide 25-29 , and compare their functions and the resulting system metrics to make a comparison between them.The system under consideration as illustrated in Figure 1, contains two nitrogen-vacancy center ensemble...

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Generating Multimode Entangled Microwaves with a Superconducting Parametric Cavity

Cited by 49 publications

References 45 publications

Observation of Three-Photon Spontaneous Parametric Down-Conversion in a Superconducting Parametric Cavity

Observation of Three-Photon Spontaneous Parametric Down-Conversion in a Superconducting Parametric Cavity

Criteria to detect genuine multipartite entanglement using spin measurements

Hybrid spin-superconducting quantum circuit mediated by deterministically prepared entangled photonic states

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