Unitary Evolution and Elements of Reality in Consecutive Quantum Measurements
Probabilities of the outcomes of consecutive quantum measurements can be obtained by construction probability amplitudes, thus implying the unitary evolution of the measured system, broken each time a measurement is made. In practice, the experimenter needs to know all past outcomes at the end of th...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-06-01
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| Series: | Entropy |
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| Online Access: | https://www.mdpi.com/1099-4300/24/7/877 |
| _version_ | 1797406570415390720 |
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| author | Dmitri Sokolovski |
| author_facet | Dmitri Sokolovski |
| author_sort | Dmitri Sokolovski |
| collection | DOAJ |
| description | Probabilities of the outcomes of consecutive quantum measurements can be obtained by construction probability amplitudes, thus implying the unitary evolution of the measured system, broken each time a measurement is made. In practice, the experimenter needs to know all past outcomes at the end of the experiment, and that requires the presence of probes carrying the corresponding records. With this in mind, we consider two different ways to extend the description of a quantum system beyond what is actually measured and recorded. One is to look for quantities whose values can be ascertained without altering the existing probabilities. Such “elements of reality” can be found, yet they suffer from the same drawback as their EPR counterparts. The probes designed to measure non-commuting operators frustrate each other if set up to work jointly, so no simultaneous values of such quantities can be established consistently. The other possibility is to investigate the system’s response to weekly coupled probes. Such weak probes are shown either to reduce to a small fraction the number of cases where the corresponding values are still accurately measured, or lead only to the evaluation of the system’s probability amplitudes, or their combinations. It is difficult, we conclude, to see in quantum mechanics anything other than a formalism for predicting the likelihoods of the recorded outcomes of actually performed observations. |
| first_indexed | 2024-03-09T03:27:17Z |
| format | Article |
| id | doaj.art-55ebcfbcccb64802883534b55615a852 |
| institution | Directory Open Access Journal |
| issn | 1099-4300 |
| language | English |
| last_indexed | 2024-03-09T03:27:17Z |
| publishDate | 2022-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Entropy |
| spelling | doaj.art-55ebcfbcccb64802883534b55615a8522023-12-03T15:00:03ZengMDPI AGEntropy1099-43002022-06-0124787710.3390/e24070877Unitary Evolution and Elements of Reality in Consecutive Quantum MeasurementsDmitri Sokolovski0Departmento de Química-Física, Universidad del País Vasco, UPV/EHU, 48940 Leioa, SpainProbabilities of the outcomes of consecutive quantum measurements can be obtained by construction probability amplitudes, thus implying the unitary evolution of the measured system, broken each time a measurement is made. In practice, the experimenter needs to know all past outcomes at the end of the experiment, and that requires the presence of probes carrying the corresponding records. With this in mind, we consider two different ways to extend the description of a quantum system beyond what is actually measured and recorded. One is to look for quantities whose values can be ascertained without altering the existing probabilities. Such “elements of reality” can be found, yet they suffer from the same drawback as their EPR counterparts. The probes designed to measure non-commuting operators frustrate each other if set up to work jointly, so no simultaneous values of such quantities can be established consistently. The other possibility is to investigate the system’s response to weekly coupled probes. Such weak probes are shown either to reduce to a small fraction the number of cases where the corresponding values are still accurately measured, or lead only to the evaluation of the system’s probability amplitudes, or their combinations. It is difficult, we conclude, to see in quantum mechanics anything other than a formalism for predicting the likelihoods of the recorded outcomes of actually performed observations.https://www.mdpi.com/1099-4300/24/7/877quantum measurementsunitary evolutionsquantum elements of reality |
| spellingShingle | Dmitri Sokolovski Unitary Evolution and Elements of Reality in Consecutive Quantum Measurements Entropy quantum measurements unitary evolutions quantum elements of reality |
| title | Unitary Evolution and Elements of Reality in Consecutive Quantum Measurements |
| title_full | Unitary Evolution and Elements of Reality in Consecutive Quantum Measurements |
| title_fullStr | Unitary Evolution and Elements of Reality in Consecutive Quantum Measurements |
| title_full_unstemmed | Unitary Evolution and Elements of Reality in Consecutive Quantum Measurements |
| title_short | Unitary Evolution and Elements of Reality in Consecutive Quantum Measurements |
| title_sort | unitary evolution and elements of reality in consecutive quantum measurements |
| topic | quantum measurements unitary evolutions quantum elements of reality |
| url | https://www.mdpi.com/1099-4300/24/7/877 |
| work_keys_str_mv | AT dmitrisokolovski unitaryevolutionandelementsofrealityinconsecutivequantummeasurements |