4 research outputs found
μΈ‘μ κΈ°κΈ°μ 무κ΄ν μμμ‘°μ κ³Ό μμ μ±λμ‘°μ μ κ²μ¦
νμλ
Όλ¬Έ(λ°μ¬)--μμΈλνκ΅ λνμ :μμ°κ³Όνλν 물리·μ²λ¬ΈνλΆ(물리νμ 곡),2020. 2. μ νμ.λ³Έ λ
Όλ¬Έμ μμ€μ 견λ μ μλ μμμ‘°μ κ³Ό μμ μ±λμ‘°μ μ λν΄ μΈ‘μ κΈ°κΈ°μ 무κ΄ν κ²μ¦λ°©λ²μ μ 곡νλ κ²μ λͺ©νλ‘ μΌκ³ μλ€. λ³Έ λ
Όλ¬Έμμλ μμ λΉκ΅μμ±μ κ°λ
λ€κ³Ό, κ²μ¦κ³Όμ μ μμ΄μ κ°μ λλ μ λ’°μ±μ μ¬λΆμ λ°λΌ λΉκ΅μμ±μ λ²μ£Όλ₯Ό λΆλ₯ν μ μμμ μ΄ν΄λ³Έλ€. κ²μ¦μ μ°Έμ¬νλ λͺ¨λ κ²μ¦μλ₯Ό μ λ’°ν μ μμλ κ²μ¦νλ μμ λΉκ΅μμ±μ μμμ½νμ΄λΌκ³ νκ³ , λͺ¨λ κ²μ¦μλ₯Ό μ λ’°ν μ μμ λ κ²μ¦νλ μμ λΉκ΅μμ±μ 벨 λΉκ΅μμ±μ΄λΌκ³ νλ©°, λͺλͺ κ²μ¦μλ μ λ’°ν μ μμΌλ λλ¨Έμ§ κ²μ¦μλ μ λ’°ν μ μλ κ²½μ°μ κ²μ¦νλ μμ λΉκ΅μμ±μ μμμ‘°μ μ΄λΌκ³ νλ€. μ΄λ¬ν κ΄μ μμ μμμ‘°μ μ 벨 λΉκ΅μμ±κ³Ό μμμ½νμ κ°μ΄λ°μ μμΉνλ λΉκ΅μμ±μ΄λ€. λΉκ΅μμ νμμ 보μ¬μ€ μ μλ μμμνμ κ΄μ μμ λ§νλ€λ©΄, μμμ‘°μ μ΄ κ°λ₯ν μνλ€μ μ§ν©μ 벨 λΉκ΅μμ μνλ€μ μ§ν©λ³΄λ€ ν¬κ³ , μμ μ½νμ΄ μλ μνλ€μ μ§ν©μ μμμ‘°μ μ΄ κ°λ₯ν μνλ€μ μ§ν©λ³΄λ€ ν¬λ€. μ΄λ ν μ΄μ λ‘ μΈν΄ λͺ¨λ κ²μ¦μλ₯Ό μ λ’°ν μλ μλ μν©μ΄λΌλ©΄ μμμ½νμ κ²μ¦μ λΆκ°λ₯νκ³ , λ°λΌμ λ¨κ²λλ μ νμ§λ μμμ‘°μ μ΄λ 벨 λΉκ΅μμ±μΌλ‘ μ’νμ§λ€. λ°λΌμ μμμ‘°μ μ νΉμ κ²μ¦μλ₯Ό μ λ’°ν μ μλ μν©μμ μ΅λν λ§μ μμμνλ₯Ό μ νμ§λ‘ ν보νκ³ μΆμ λ μ μ©νκ² νμ©λ μ μλ λΉκ΅μμ±μ λ²μ£Όμ΄λ€.
ννΈ μμμ½νκ³Ό μμμ‘°μ μ κ²μ¦μ μμ΄ νΉμ κ²μ¦μλ₯Ό μ λ’°ν μ μμ΄μΌ νλ€λ μꡬ쑰건μ μννμ¬, νΉμ μμμνλ₯Ό μ μμ±ν μ μμ΄μΌ νλ€λ μꡬ쑰건μΌλ‘ λ체νλ κ²μ¦ λ°©μμ΄ μ‘΄μ¬νλ€. μΈ‘μ κΈ°κΈ°μ 무κ΄ν κ²μ¦μ΄λΌκ³ λΆλ¦¬λ μ΄λ¬ν κ²μ¦ λ°©λ²μ λΉκ΅μμ± λμ΄μμ μ
λ ₯κ°μ κ³ μ μ λ³΄κ° μλ μμ μνλ‘ λ°κΎΈλ λ°©μμΌλ‘ μ΄λ£¨μ΄μ§λ€. λμ΄μ μ°Έμ¬μλ€μ μ
λ ₯λ μμμνλ₯Ό λͺ
ννκ² κ΅¬λΆ ν λ°©λ²μ΄ μμΌλ―λ‘, λΉκ΅μμ μμμνλ₯Ό 곡μ νμ§ μλλ€λ©΄ λμ΄μμ λμ μ μλ₯Ό μ»μ§ λͺ»νκ² λκ³ λ°λΌμ λΉκ΅μμ±μ κ²μ¦μ ν΅κ³Όν μ μλ€.
λ³Έ λ
Όλ¬Έμμλ μΈ‘μ κΈ°κΈ°μ 무κ΄ν κ²μ¦λ°©λ²μ μμ€μ 견λ μ μλ μμμ‘°μ μ μ λͺ©νμλ€. μ΄λ κ² κ΅¬μ±λ μμμ‘°μ μ κ²μ¦μ μμ€μ 견λ μ μλ νΉμ±κ³Ό μΈ‘μ κΈ°κΈ°μ 무κ΄ν νΉμ±μ λͺ¨λ κ°μ§λ©°, μ‘°μ λλ κ²μ¦μμκ²μ μ‘°μ νλ κ²μ¦μμκ² μ 보 μ μ‘μ νμ©νλλΌλ μ ν¨νκ³ , μ¬μ§μ΄ μμ μνμ μμ±μ΄ λΆμμ νλλΌλ μ¬μ ν μ ν¨ν¨μ λ³΄μΌ μ μλ€. λΆμμ ν μμμνμ μμ±μ΄ μμμ‘°μ μ κ²μ¦μ λ―ΈμΉλ μν₯μ λ νλΉ μν©μμ μννμλ€. μ΄λ¬ν μμμ‘°μ μ κ²μ¦μ μμ€μ 견λλ νΉμ±μ΄ λΉλμΉμ μΈλ°, μ‘°μ λλ κ²μ¦μκ° κ²ͺλ μμ€μ κ²μ¦μ μν₯μ λΌμΉμ§ μμΌλ μ‘°μ νλ κ²μ¦μκ° κ²ͺλ μμ€μ 견λκΈ° μν΄μλ μμμ‘°μ μ κ²μ¦λ°©μμ μ μ ν μ¬κ΅¬μ±ν΄μΌλ§ νλ€. μ΄λ¬ν λΉλμΉμ±μ λΉλμΉμ μΈ μμ μ 보μ²λ¦¬ κ³Όμ μ μμ©λ μ μμΌλ©°, μμ€μ 견λ μ μλ νΉμ±κ³Ό μΈ‘μ κΈ°κΈ°μ 무κ΄ν νΉμ±μ μ‘μμ΄ λ§κ³ ν΅μ ν μ μλ νκ²½μμ λΉκ΅μμ±μ κ²μ¦μ ꡬννλ λ° λμμ΄ λ κ²μ΄λΌκ³ κΈ°λλλ€.
ννΈ μ°λ¦¬λ μμ λΉκ΅μμ±μ κ°λ
μ μμ μ±λλ‘ νμ₯νμ¬, μΈ‘μ κΈ°κΈ°μ 무κ΄ν μμ μ±λμ‘°μ μ λ°©λ²μ μ μνμλ€. μ΄λ₯Ό μν΄ μνκ° μλ μ§ν©μ²΄ κ°λ
μ μ±ννμ¬ λ¬Έμ μ μ κ·Όνμκ³ , μ΅-μλ―Έμ¬μ½νμ€ν€ λνμ¬μμ μ΄μ©νμ¬ μ±λ μ§ν©μ²΄κ° μμμ‘°μ κ°λ₯νλ€λ μ¬μ€κ³Ό μλ μμμν μ§ν©μ²΄κ° μμμ‘°μ κ°λ₯νλ€λ μ¬μ€μ΄ λμΉμ‘°κ±΄μμ μ¦λͺ
νμλ€. κ·Έ λ€ μ μ 리λ μΈ‘μ κΈ°κΈ°μ λ
립μ μΈ κ²μ¦λ°©μμ μλ μμμνμ μ μ©νμ¬ μΈ‘μ κΈ°κΈ°μ λ
립μ μΈ μ±λ μ‘°μ μ κ²μ¦μ μμνλ€. λμκ° λΆμμ ν μμμνμ μμ±μ΄ μΈ‘μ κΈ°κΈ°μ λ
립μ μΈ κ²μ¦μ λ―ΈμΉλ μν₯μ λΆμνμλλ°, νΉν μ΅-μλ―Έμ¬μ½νμ€ν€ λνμ¬μμ μ»λλ° μ°μ΄λ μμμνμ μ§μ€νμλ€. κ·Έ κ²°κ³Ό λͺ©νλ‘ μΌμλ μμν μμμνλ₯Ό μμ±ν΄λ΄μ§ λͺ» νκ³ λ€λ₯Έ μμμνλ₯Ό λ§λ€λλΌλ, λ κ³ μ¬μ΄μ μμν μμμνκ° κ½ μ°¬ μλ―ΈνΈ λν¬λ₯Ό κ°μ§κΈ°λ§ νλ€λ©΄ κ²μ¦κ³Όμ μλ μ΄λ ν λ¬Έμ λ μΌμΌν€μ§ μμμ 보μκ³ , κ΅μμ μΈ μ‘μκ³Ό μμ΄λ κ²½μ° μ΄λ μ λμ μ‘μμ λΉμ¨κΉμ§λ 견λ μ μμμ 보μλ€. μ΄λ 견λ μ μλ μ‘μμ λΉμ¨μ ννμ μ΄λ―Έ μ μλ €μ Έ μλ μ‘°μ μ΅μ
λλ‘ κ²°μ λλ€. μΆκ°μ μΈ μ°κ΅¬ λ°μ λ°©ν₯μ μνμ¬ μμμ‘°μ μ΅μ
λ λ° κ·Έμ μ μ¬ν ννμ 물리λκ³Ό, μμμ‘°μ λ° μ΅-μλ―Έμ¬μ½νμ€ν€ λνμ¬μκ³Ό κ΄λ ¨λ λͺ κ°μ§ λ―Έν΄κ²° λ¬Έμ λ€μ λμ Έλμλ€. μΈ‘μ κΈ°κΈ°μ 무κ΄ν μμ μ±λμ‘°μ μ κ²μ¦μ ν΅μ ν μ μκ³ μ‘μμ΄ λ§μ μν©μμ μμ μ±λμ μμμ λ³΄κ° λμΆλλ μν©μ νμΈνλλ° μ μ©νκ² μ¬μ©λ κ²μΌλ‘ κΈ°λλλ€.This dissertation aims to provide measurement-device-independent verification protocol for loss tolerant quantum steering and quantum channel steering. We review the concepts of quantum nonlocality, and see that we can classify it into the three depending on the assumption that the party who participates in verification protocol is trustworthy. If the quantum nonlocality is verified when every party is trusted, we call it quantum entanglement, if it is verified when every party is untrusted, we call it Bell's nonlocality, and if it is verified when some parties are trusted while the others are not, we call it quantum steering. In this respect, quantum steering lies in the intermediate position between Bell's nonlocality and quantum entanglement. In view of quantum states which can display nonlocal phenomenon, we can say that the set of steerable states is larger than the set of Bell nonlocal state, and the set of entangled states is larger than the set of steerable states. For some situations that we cannot trust everybody, entanglement verification is impossible, thus our option is steering or Bell's nonlocality. Therefore, quantum steering can be useful when some party cannot be trusted and we need broad choice of quantum states to exploit quantum nonlocality.
In the meantime, there is another verification protocol of quantum nonlocality that we can relieve the trust assumption at the cost of quantum state generation. This protocol, called measurement-device-independent verification protocol, is constructed with nonlocal game approach where classical input is replaced with quantum states. The participants of the game can distinguish the input states only if they share quantum nonlocal states, thus their success in the game, obtaining the high score, is an indicator of quantum nonlocality of the shared states.
We apply measurement-device-independent protocol for loss-tolerant steering inequality. As a result, we construct quantum steering verification protocol to be measurement-device-independent and loss-tolerant. The verification is valid even if we allow one-way communication from the steered party to the steering party and generation of input quantum states is imperfect. The effect of imperfect generation of input quantum states to the verification protocol is quantified for two qubit setup. The resultant steering criterion is asymmetric with respect to measurement efficiencies because the measurement efficiency of the steered party does not affect the verification protocol while that of the steering party does. Therefore, to make the steering verification loss-tolerant with respect to the steering party, we have to reformulate it appropriately according to the heralding efficiency of the steering party. The measurement-device-independent and loss-tolerant properties can help implement steering verification in uncontrollable and lossy environment, and asymmetric property will be useful for asymmetric quantum information processing tasks.
Moreover, we extend the concept of quantum nonlocality to quantum channels, and propose measurement-device-independent verification protocol of quantum channel steering. For this purpose, we adopt assemblage approach and utilize Choi-Jamiolkowski isomorphism. We prove that channel assemblage is steerable if and only if its dual state assemblage is steerable. We then apply canonical method of measurement-device-independent verification protocol to the obtained dual state assemblage. In this way we accomplish measurement-device-independent verification of channel steering. We further inspect the effect of imperfect quantum state generation, especially for which is used to obtain Choi-Jamiolkowski isomorphism. As a result, we show that the channel-state duality of steering holds as long as the quantum state is bipartite pure state with full Schmidt rank. Furthermore, mixture of the quantum state with local noise is tolerable up to some proportion, which is bounded from below by the steering robustness. For further researches, some open questions regarding the Choi-Jamiolkowski isomorphism and steering are listed. We expect that the results can be exploited to check leakage of quantum information in quantum channels under lossy and uncontrollable environment.I. Introduction 1
II. Quantum Nonlocality 5
2.1 Introduction 5
2.2 Category of Quantum Nonlocality 11
2.3 Extended Concepts of Quantum Steering 17
III. Measurement-device-independent verification of quantum nonlocality 21
3.1 Introduction 21
3.2 Nonlocal Game 21
3.3 Semi-Quantum Nonlocal Game 25
3.4 Quantum Refereed Steering Game 32
IV. Measurement-Device-Independent and Loss Tolerant Verification of Quantum Steering 39
4.1 Introduction 39
4.2 Loss Tolerant QRS game 40
4.2.1 Loss Tolerant Steering Inequality 40
4.2.2 Loss Tolerant QRS game 43
4.3 Remarks 48
V. Channel Steering 51
5.1 Incoherent channel 51
5.2 Channel Steering 53
5.3 Remarks 66
VI. Conclusion 69
Bibliography 85
Abstract in Korean 85Docto