External-level assisted cooling by measurement

Yan, Jia-shun; Jing, Jun

doi:10.1103/physreva.104.063105

Cited by 11 publications

(5 citation statements)

References 62 publications

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“…When those dynamics can be arbitrarily controlled, the system can always trivially be cooled; this is because adding an auxiliary system, performing an arbitrary joint interaction, then ignoring or measuring the arbitrary system allows one to enact an arbitrary quantum channel on a given quantum system to generate any desired state [63] and strongly violates the assumptions of HBAC. The HBAC can also be replaced by any other procedure that helps to serially cool a quantum system toward its ground state, including other measurement-based protocols [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. Third, HBAC protocols have recently been shown to potentially benefit from the presence of environmental noise [12].…”

Section: Discussionmentioning

confidence: 99%

“…However, this naive picture is too simplistic, as it requires n ideal binary-outcome measurements to purify n qubits. Alternative measurement-based purification schemes exist that require many measurements or only converge toward the purest state [16][17][18][19][20][21][22][23][24][25][26][27][28], such as a recent idea that proposes to perform ?n measurements on a single auxiliary qubit to purify n qubits (with some finite success probability that decays exponentially with n) [29] and one that seeks to reduce the number of measurements by using techniques from reinforcement learning [30]. In comparison, our method can completely purify n qubits with a single binary measurement (and arbitrarily high success probability).…”

Section: Introductionmentioning

confidence: 99%

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Breaking the limits of purification: postselection enhances heat-bath algorithmic cooling

Goldberg

Heshami

2023

J. Phys. Commun.

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Quantum technologies require pure states, which are often generated by extreme refrigeration. Heat-bath algorithmic cooling is the theoretically optimal refrigeration technique: it shuttles entropy from a multiparticle system to a thermal bath, thereby generating a quantum state with a high degree of purity. Here, we show how to surpass this hitherto-optimal technique by taking advantage of a single binary-outcome measurement. Our protocols can create arbitrary numbers of pure quantum states without any residual mixedness by using a recently discovered device known as a quantum switch to put two operations in superposition, with postselection certifying the complete purification.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Breaking the limits of purification: postselection enhances heat-bath algorithmic cooling

Goldberg

Heshami

2023

J. Phys. Commun.

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“…This result limits the range of application in terms of the initial temperature or occupation of the target resonators. To address the cooling-range problem in measurement-based cooling, one might resort to either introducing extra measurement-based cooling by strongly coupling the excited state of the ancillary system to an external level [31] or optimizing the measurement-interval τ as we will focus on in the next section.…”

Section: Cooling Model and Coefficientmentioning

confidence: 99%

Simultaneous cooling by measuring one ancillary system

Yan,

Jing

2022

Preprint

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We present a simultaneous-cooling protocol for a double-resonator system via projective measurements on an ancillary V -type qutrit. Through repeated measurements on the ground state of the ancillary system, the two resonators can be cooled down to their respective ground states from thermal states. With respect to the measurement-based cooling, an optimized measurement-interval τopt is analytically obtained for the first time, which is inversely proportional to the collective thermal Rabi frequency Ω th as a function of the resonators' average population of the last round. Under about only 20 optimized measurements, the average population of the target resonators can be reduced by 6 orders in magnitude. Our simultaneous or collective cooling protocol is scalable to the systems with more numbers of resonators and robust to the fluctuation in the resonator frequency.

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“…In another word, the resonator is gradually steered by the outcomes of the conditional measurement (CM) to its ground state via dynamically filtering out its vibrational modes. Ranging from cooling the nonlinear mechanical resonators [20], cooling by one shot measurement [21], expanding cooling range by an * Email address: jingjun@zju.edu.cn external driving [22], to accelerating cooling rate by optimizing the measurement intervals [23], an unexplored weakness of all these CM strategies is their small successful probability inherited from the projective operation (postselection). An inevitable amount of cost rises with more samples in ensemble.…”

Section: Introductionmentioning

confidence: 99%

Optimize cooling-by-measurement by reinforcement learning

Yan,

Jing

2022

Preprint

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Cooling by the conditional measurement demonstrates a transparent advantage over that by the unconditional counterpart on the average-population-reduction rate. This advantage, however, is blemished by few percentage of the successful probability of finding the detector system in the measured state. In this work, we propose an optimized architecture to cool down a target resonator, which is initialized as a thermal state, using an interpolation of the conditional and unconditional measurement strategies. Analogous to the conditional measurement, an optimal measurementinterval τ u opt for the unconditional (nonselective) measurement is analytically found for the first time, which is inversely proportional to the collective dominant Rabi frequency Ω d as a function of the resonator's population at the end of the last round. A cooling algorithm under the global optimization by the reinforcement learning results in the maximum value for the cooperative cooling performance, an indicator function to quantify the comprehensive cooling efficiency for arbitrary cooling-by-measurement architecture. In particular, the average population of the target resonator under only 16 rounds of measurements can be reduced by over four orders in magnitude with a successful probability about 30%.

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External-level assisted cooling by measurement

Cited by 11 publications

References 62 publications

Breaking the limits of purification: postselection enhances heat-bath algorithmic cooling

Breaking the limits of purification: postselection enhances heat-bath algorithmic cooling

Simultaneous cooling by measuring one ancillary system

Optimize cooling-by-measurement by reinforcement learning

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